Pressure Works.............

[Michael458]

Some few weeks ago looking shopping around for some extra supplies to lay in, I ran across some decent looking 308 caliber 125 gr Hornady red tip bullets, they have a name, but I can't recall it just now, so will just call them Red Tips! Good price, available, so I bought 5 boxes of them. I was having a vision of "MAYBE" these would give a close enough POI with the #1 100 Raptor load to make it worthwhile, and thinking 300 BLK, 7.62X40, and 308 Winchester.

I decided to test all these loads for pressures and consistency.

I have not loaded many heavy bullets in 300 BLK, the 100 Raptors are extreme, and I get great POI with several different 110 bullets, in 300 BLK there really is not much need for heavier bullets, for my purposes. 300 BLK was not a high priority with these 125s, but more or less something to just play with a bit. I did a couple of loads with LilGun. The first one exceeded my standard pressures for the cartridge at 57000 PSI, I dropped 1/2 grain and average pressure dropped to 51600, but there was an extreme spread of 5200 PSI, which exceeds my standards. For now I will put this way on the back burner for 300 BLK...............

After the 300 BLK I did some work with the 7.62X40, but really didn't like how deep I have to seat the bullet to get them to function in either magazines, or the bolt guns. It's workable, and not a major point, but would have liked it better not seated so deep.
LilGun has become a great powder for this cartridge, gives me about a 100 fps more than I can get with WW 296 at considerable less pressure, with 100 Raptors and various 110 gr bullets. But LilGun also gave some large extreme spreads with this 125 gr bullet. Velocity spread was not so bad, but pressure extremes where out of spec.

I moved to CFE BLK. Running 25/CFE Black I managed 2346 fps at 43500 PSI, very low pressure. Bumping up to 26/CFE BLK gave me 2425 fps at 48800 PSI with the 125s. All extremes were well within spec and the load looks good. The only problem I might see is that POI shifted with the 26/CFE BLK load to OUT OF SPEC compared to the 25/CFE BLK. Something to check later at 50 yards. 26/CFE BLK is about as much as I can get in the case.......

Moving on to 308 Winchester, I had 3 loads to run through here with the 125 Hornady. 48/AA 2520 giving 3092 AT 54500 PSI all within spec, 46/Benchmark for 3128 fps at 55500 PSI, and 46/IMR 8208 for 3085 fps at 48000 PSI. All these loads gave acceptable spreads and consistency as well. However in 308 Winchester in a variety of different rifles we run, we like to stay at or below 52000 PSI, which seems to run various rifles better, some of these rifles get sticky and hateful at 54000. As you might
discern, I am partial to the IMR 8208 load at considerable less pressure, and not that much less velocity at 48000 PSI.

While I was running things I had a lot of 416 B&M on the bench, test loads of Norma and Quality brass, mostly with WW 748 and 300 gr Barnes TSX, 350 Barnes TSX and 340 Woodleigh PP. The 416 B&M is based on a cut, trim, and formed RUM case. Big differences in various brass occur, especially now that Remington is no longer making RUM brass, and it is being made by Norma, Hornady and Nosler. Of the three, we really like the Norma brass. It has proven in every case to give higher velocity with any given load, at some less pressure than even the parent Remington brass. There are many tests I have run on different variables. One of these is the difference between NEW FORMED brass and Once fired brass. For example......

Norma NEW FORMED 416 B&M
300 gr Barnes TSX 74/WW 748 2532 fps at 51900 PSI

Norma Once Fired 416 B&M
300 gr Barnes TSX 74/WW 748 2498 fps at 48800 PSI

While not an incredible amount, 3000 PSI is something to be considered, especially when you get to full on top end loads approaching 65000 PSI Max.......Which I very rarely come close to that with any of my cartridges. Normally I top them out at 60000-62000 with heavy loads. Most big bore loads with lighter bullets rarely exceed 55000 PSI, its just not required in the field.

Another thing that concerns brass, some of my Quality 416 B&M head stamped brass opens a little scratchy, which could be considered a sign of pressure, if you didn't know better. I had some of this going on pressures all less than 55000 PSI. So not even close, and of course the same load with Norma opens smooth as silk.

One interesting test (by accident) was a load with 350 gr Barnes TSX and 78/WW 748. I only had two rounds, big difference between the two rounds, when I looked, one was Norma brass and the other was Hornady brass........

Norma 2480 fps at 54400 PSI. Hornady 2436 fps at 52800 PSI. While this is well within spec with pressures, I did not care for the spread in velocity between the two. Just the difference in brass, with is what I have found with all the Hornady, its thinner, and has more capacity. It can be brought up to speed, but requires adding powder for specific Hornady brass, something I would rather avoid.

Its always fun, and a big learning experience every session I test these things.......

My chicken scratching........ All these get transferred to Load spreadsheets I keep on every cartridge/firearm..........

 

[Hashknife]

Good stuff Mike!!

Thx for the testing info. The 7.62 x 40 is an awesome cartridge.

 

[Goofyfoot2001]

Do you have to drill a hole in your barrel?

 

[Michael458]

Do you have to drill a hole in your barrel?

No, they work with strain gages.

@Hashknife, I am a fan of the 7.62X40 as well. Have lots of data if you need it........ But mostly with 100 Raptors and various 110s.......

 

[Toprudder]

No, they work with strain gages.

I’m curious, how do you calibrate something like that?

 

[Gator]

The knowledge that you share with us is to me, mind boggling. Always enjoy learning from you.

.

 

[Catfish]

I’m curious, how do you calibrate something like that?

I think he could write a book on that. and if he does, I'll buy one! just sayin'

 

[Get Off My Lawn]

Do you have to drill a hole in your barrel?

Yes.
The bullet goes in one end of the hole, and comes out the other.

 

[Michael458]

I’m curious, how do you calibrate something like that?

If you are speaking about the system, the Oehler and RSI 1 are both stand alone, what you see is what you get, no calibration needed. There are some parameters you can set within the software to adjust as required, such as the pressure held in the brass, normally between 7000-10000 PSI, and some minor things like that.

The RSI II needs to be calibrated, and I calibrate mine to match the Oehler. Several ways to do that within the program parameters.

Once pressure with a particular rifle and load is established with a stand alone system, Oehler and RSI I, then you hook up the rifle to the RSI II System, fire the same load. Then easy enough to adjust the parameters until the pressure on that test matches with the Oehler/RSI I pressure, then retest. Once that is done, that rifle is calibrated to the RSI II system from that point on.

Strain gages all come with the same values and parameters, its just a matter of getting it glued to the barrel properly. Within the various programs you have to plug in some values, such as barrel diameter at the point of the gage attachment, and such as that.......

Its not really a big ugly deal. It is always one of my favorite things, it is just incredible what you learn and can learn running these systems.

 

[Catfish]

An out-of-the box system that does not require calibration would need to incorporate an assumption about the elastic modulus of the steel used to make rifles yes? I suppose it must be constant enough to ignore any variations? There are only so many materials suitable for making high powered rifles.

Does the thickness of the chamber wall affect the accuracy of the readings?
Do the gauges ever require factory re-calibration?

 

[Toprudder]

If you are speaking about the system, the Oehler and RSI 1 are both stand alone, what you see is what you get, no calibration needed. There are some parameters you can set within the software to adjust as required, such as the pressure held in the brass, normally between 7000-10000 PSI, and some minor things like that.

The RSI II needs to be calibrated, and I calibrate mine to match the Oehler. Several ways to do that within the program parameters.

Once pressure with a particular rifle and load is established with a stand alone system, Oehler and RSI I, then you hook up the rifle to the RSI II System, fire the same load. Then easy enough to adjust the parameters until the pressure on that test matches with the Oehler/RSI I pressure, then retest. Once that is done, that rifle is calibrated to the RSI II system from that point on.

You adjust the RSI 2 to match the Oehler and RSI 1? How do you know those are correct. How do you know when it registers 50k psi that it is really 50k psi?

I work with lab instrumentation that goes through periodic calibrations to insure proper measurements. That is done by a calibration service with their own instruments that are traceable to NIST standards. For my own peace of mind, I often double check my test setups by comparing two similar instruments, both with calibrations traceable to NIST, for correlation.

I seem to remember reading somewhere that SAAMI sells reference loads for pressure test instrumentation.

I would really love to see your test setup, I’m sure it would help me to better understand what is going on.

 

[Michael458]

Oehler is the industry standard, and has been used many years to determine pressures. Absolute? No, nothing is ever 100% absolute when it comes to firearms pressures. Close? Reasonable? Yes. I could go on for some time about the two systems, Oehler and RSI. Especially RSI I which is a superb unit that is no longer available. There are way too many variables when it comes to chamber pressures. As for equipment, you have to be on top of it all the time, and I suppose some experience required to read and understand the strength and weakness of the systems. Gages are extremely delicate, but have been proven to measure extremely accurately as long as they have a good connection and are not damaged. At times they need to be replaced. Since I have about 20 years of dealing with these I have become pretty decent at recognizing when something is out of spec. Sometimes the connection is just lost and will give you bad readings. I always have some loads around to do periodic tests. In this session I tested some loads that were done in 2014 that I had data on. Did they test exactly the same? No. There was about 1500 PSI difference. But, that is of no consequence, as there is normally that much difference round to round. Environment can have an effect, and the same load will test slightly different from day to day. Only when you get something completely out of spec is when you start to get very curious about something, say 10000 PSI difference in a load. And in every single case that I have had that, its a strain gage that has lost its contact with the barrel.

Here is what Oehler says about Pressure...............

Chamber pressure measurement is a blend of science, black art, and common sense. There are few absolutes; the best we can expect is to reliably distinguish between the safe and the unsafe. Pressure measurements are tedious, but they must be made. Pressures will literally rise up to smite the unwary.

Shooters have a good idea of what happens in front of the gun, but they have no idea of what is going on inside the gun. If nothing breaks, it's OK; if the cartridge case can't be reloaded, it's borderline; if the gun blows up the load was a little hot. This is completely unacceptable from the viewpoint of personal safety. The wiser shooters try to "read" the indications of excess pressure by paying particular attention to the condition of the cartridge case after a shot is fired. What they don't realize is that many of the fired cases of proof ammo would be considered to be reloadable if judged by the visible characteristics commonly observed by handloaders. There are no signs of brass flow or enlarged primer pockets. Proof ammunition is special test ammo loaded to generate distinctly higher pressures than will ever be generated by factory ammo. Each new gun is tested with one round. Shooters claim concerns about pressure, but they often don't give pressure the respect it deserves. They have had no equivalent to a chronograph to help them.


Ideally, chamber pressure readings should be absolute. We are all spoiled and accustomed to absolute measurements of common items. If you buy a pound of powder you expect to get an amount that weighs exactly the same as a pound of butter from the grocery store or a pound of nails from the hardware store. Within close tolerances you will be right. All three of the items mentioned can be taken to a scale and weighed; you can repeat the comparison by weighing each item on a second scale. You can even "calibrate" the scales; it's simple to use a check weight.

Chamber pressure readings are more complicated than weighing a brick of butter. You can weigh and measure a loaded cartridge all you want to, you can fire dozens of loaded cartridges from the same lot in tightly specified pressure guns under controlled conditions, you can plead with the gods and IRS, but you still can't tell how much pressure the load will generate when fired in your gun.
You may read that the pressure of a certain load is 56,000 psi. You must not assume that the 56,000 psi is an absolute number. If the number is quoted for factory ammo you know that similar ammo was tested in accordance with ANSI/SAAMI standards and that there is little chance that the pressure of the ammo fired under ANSI/SAAMI specified conditions will exceed the 56,000 psi. The 56,000 psi number by itself does not tell you the pressure that will be generated when you fire the ammo in any specific test barrel or gun. The pressure generated by the round depends greatly on the gun in which it is fired and the test conditions. Individual chamber and barrel tolerances are critical. Even if you use three "identical" rifles with consecutive serial numbers or three SAAMI spec test barrels, I'll wager that you will get three different average velocities and average pressures. The pressure numbers so casually mentioned with great authority are not absolute; they are approximate and they are only relative!

The pressures measured in any specific gun with the either piezo transducer or strain gage apply only to that gun. You can use the pressure numbers to compare different ammo fired in the same gun with the same instrumentation. Strain gage readings from the M83 correspond closely to pressures in hundreds of pounds per square inch. Pressures in sporting gun will typically be lower than pressures of the same ammo fired in a standard test barrel because the test barrel is intentionally made tighter than typical sporting barrels. Just as some barrels shoot accurately and some won't, the same ammo builds different pressures in different barrels.

And we could go on. Basically what I said and according to Oehler as well..... when it comes to Firearms pressures, there are just not any Absolutes.

 

[Michael458]

When testing and attempting to read pressures you absolutely have to use all the tools that are available to you, and not just the Pressure equipment itself. There are so many variables that can have influence on pressures, any one, or even 1/2 dozen indicators may not be enough. As for equipment like the Oehler and RSI units, a faulty gage can really ruin your day. A gage that was not applied to the rifle properly will give false readings. One that has worked its way loose can give faulty readings, environmental factors on any given day will give different readings from the day before. And for no damn reason at all or one you cannot identify, you can get a crazy reading.

Not too long ago I was convinced I had found a "Magic Powder"......... It was a new lot of WW 296 and involving 300 BLK. I have some loads that are basic and standard in given cartridges, tested many many many times, sometimes over several years. For 300 BLK I am relatively a newcomer to this cartridge, starting in 2015. My first Pressure readings in 300 BLK was in January of 2016. My favorite and basic load with the 100 FB Raptor is 20.3/WW 296 and I can use either Federal 205 or Winchester small rifle primers. Looking back at my data, I have tested this load in both RSI and Oehler systems just less than 50 different tests. That is quite a bit actually. But it gives me a really good idea of where this is going to fall in at any given time. It is going to run close to 54000 PSI any given day, little more, little less some days. Depending on other outside variables.

Now the first pressure run with the 300 BLK I did not have a bolt gun set up at the time. I used a damned Contender 12 inch barrel (I hate those damned aggravating things). The very first test in that gun/barrel with the 100 Raptor 20.3/WW 296 Fed 205 gave me 2464 fps and 54100 PSI 1/30/2016. I continued to test other bullets, other powders and what have you for the next 10-12 days, and then I put it away. It was not my barrel, so I had to send it back, but I felt like I had enough data to do what I wanted.

In January of 2018 I set up a new 16 inch barrel Winchester M70 that I had SSK convert to 300 BLK. The first test done with the 100 FB Raptor and 20.3/WW 296 gave me 2570 fps at 55300 PSI. At the time, I thought it was close enough to the other gun/gage to work. It was only 1300 PSI higher, and close enough to my Spec limit of 55000. I mean the next day it might have been under that most likely.

I did not test the load again until February of 2018 and the same load gave me 2564 fps at 54000 PSI even! OK, good to go............

In August 2018 I tested again, not sure I remember why, but once again spot on the money, 2573 fps at again dead even 54000 PSI.

In October I was testing various brass and Winchester primers, and I got slightly less velocity and pressures, 2645 fps and 51200 PSI??? With a change in brass, change in primers, I did not look closer.

January 2019 I was testing some more 300 BLK, and now the same load was giving 2549 fps and 48000 PSI???? Now I was beginning to question things! I also just happened to have opened a NEW KEG of WW 296! OMG, have I opened a MAGIC keg of powder perhaps? I have actually had a Magic Keg some years ago with 500 MDM, so I have had this in the back of my mind for YEARS. Magic Powder! So I stared experimenting, increasing the charge to see
just where I could take this NEW KEG OF MAGIC................Over the course of 5 days I had taken it up to 21.5/WW 296 for 2612 fps and pressures not increasing????? Actually DROPPING to a low of 42000 PSI.

OK, this is not Magic Powder, there is but one instance of a type of powder that when you increase and compress you get less pressure, but you also get less velocity. I don't know of an instance where you increase powder charge, get more velocity, and get less pressure! No, there is always a cost or a reason that can be identified. My brass was not looking happy either! Another indicator of a problem!

I decided to remove the strain gage and put a NEW GAGE in its place.

With the new Strain gage on, I tested in February 2019 and the load came back within spec of 2551 fps and 55400 PSI. I was also using MilSpec brass, so slightly higher pressure was expected. I also tested some loads I had with 20.5/WW 296 pressures went up as would be normal to 56500 PSI. And again with various components changing the same load would be anything from 54000 to 55400 PSI depending on brass, primer and other factors. I was some
disappointed that I had not found a Magic Keg of powder, but yet on the other hand I was quite relieved that I had NOT. I hate inconsistencies in powder from one keg to the next, some powders are just that. At least WW 296 seems to be very consistent in that, and I was happy that it is so. Regardless I normally test a new keg of powder any time I open one before loading. I have found the Alliant powders extremely inconsistent not just Lot to Lot, but Keg to keg in the same lot, some dangerously so.

This past week as stated above I was playing with the 125 Hornady. I always have loads on the range for various reasons, mostly to sight different guns in, or different scopes or sight systems, or just to check sights. I had a bag full of 100 Raptors that were loaded in 2018 with 20.3/WW 296. I decided to run a check on those and behold 2545 fps at dead even 54000 PSI................54400 Hi 53800 Lo 600 ES and average 54000 PSI.

 

[Howland]

I love the technical jargon that is incomprehensible to the target audience.

Pressures will literally rise up to smite the unwary.

You are way ahead of the vast majority of us with the capability to measure chamber pressures. We appreciate you sharing this knowledge.

 

[BatteryOaksBilly]

I love the technical jargon that is incomprehensible to the target audience.



You are way ahead of the vast majority of us with the capability to measure chamber pressures. We appreciate you sharing this knowledge.

Nothing to this at all. Y'all are giving him WAY too much credit. All that is required to do this kinda stuff is 20 years of intense experimentation with an expenditure of around $200,000. Easy Peasy!!!!

 

[Michael458]

You are way ahead of the vast majority of us with the capability to measure chamber pressures. We appreciate you sharing this knowledge.

Indeed the tools I have to work with are just incredible, and the ultimate in gathering load data, no doubt about it. But, one cannot forget the other methods that are used as a check to the data you are receiving, good old fashion
methods all of us can, and do use.

Use what you already know about reading signs of excessive pressures. Hard opening bolts, expanded primer pockets, measured case head expansion, shiny ejector hole spots, and other classic indicators of high pressures are still valid. Any of these signs is an indication of high pressure. But still not an absolute.

In the beginning of the B&M cartridges I was somewhat lazy when it came to actually doing pressure work. In some cases this worked just fine, and in others it was nearly an embarrassment. I will tell you about both.

In the beginning with 50 B&M, 458 B&M and 416 B&M I did not use the pressure equipment to get actual pressures. The primary method I used was "case measurement"........ Now with each type cartridge, there is no set method to do this, it is something you have to experiment with, and learn by using all factors that you can gather. These B&Ms were based from RUM cases, and they were cut and trimmed shorter to 2.240 inches. This in and of itself changes dynamics of how a cartridge behaves, brass is much thicker at 2.240 than it is at full length. There was no such thing as these, no factory ammo, no nothing to start with, all trail and error. I also learned at this point you could not take factory 300 RUM ammo, shoot it, measure it, and expect to have anything much to learn from that. Big difference in NEW Unfired brass expansion, and fired B&M brass expansion. New brass was close, but did not relate at all to fired and sized brass. Basically fired and sized ended up expanding 1/2 of what new expanded and that would be MAX pressures. The rifles would speak to you once you when beyond a certain point by scratching hard bolt lift. And it was fortunately rather consistent with 458 and 416. 50 B&M was a different story, it was rare, and I honestly don't even remember a bolt getting stiff to open with those.

Eventually I was able to establish with fired brass if I measured brass, from unfired to fired and it expanded .002-.0025 at the case head, then this was MAX working pressures. New unfired brass would measure as much as .005 at MAX.

I developed all the 50 B&M, 458 B&M and 416 B&M using case measurements and listening to what the rifle was telling me. Rarely did I get to the point of having flat primers, blown primers, locked up guns, or bright ejector marks on the brass.

I think it might have been 2008 or so that a fellow was interested in doing a short article on the 458 B&M. Aaron Carter, and at the time he was working with one of the NRA magazines, Shooting Illustrated, or something like that. I have copies, but at this moment just going from memory. Anyway, this was an OH CRAP moment, and I thought I might should get serious and get my S$*T together properly. So I hooked up a 458 B&M and started testing hard and furious
and checking my loads and data. Well I received very very good results and my methods had worked damn near spot on the money! Like its parent case, I consider these B&Ms able to go to 65000 PSI MAX PRESSURES. In reality I never go to that MAX, I normally MAX these loads out at 60000-63000 PSI leaving just a little room for any environmental factors that might crop up in the field or other factors. All the loads that I maxed out with the measuring method and listening to what the rifles were telling me came to 59000 to 61000 PSI! I was getting the velocity and terminals I wanted with the various bullets used, and just so happened the pressures were well within spec. I then sent everything to Aaron, he did the short article and everything was good............

With each cartridge one has to develop your own max measurements, which can be done, as long as you are methodical about the process. Look at ALL Factors, and take everything into account and it can be done without the Pressure testing equipment. In this particular case I used my tools to validate and not to develop.

Of course, after this, I really went to it with load data with all the cartridges for the bolt guns. 1000s of loads and different bullets have been tested in every way possible, almost.... there is always something more to learn, even today.....

This Winchester M70 20 inch 458 B&M has done ALL the load data Pressure work for the 458 B&M. This is still the original strain gage applied in 2008! I do check it with established loads from time to time, but it has never failed, and I don't see how in the world it has survived 1000s of rounds fired. But it has. You also see another strain gage on the end of the barrel. This strain gage was used to test "Barrel Strain" of bullets as they passed that point. This told us how much a particular bullet would bulge or stretch the barrel as it passed that point. This was of use with different band configurations in bullet design, bearing surface. This helped design the Cutting Edge band designs for Double Rifles, and to lower pressures with the band designs by reducing bearing surfaces.

I recently tested Norma brass in this gun.

 

[Fess]

Not too long ago I was convinced I had found a "Magic Powder".........

You must have done something to make the magic disappear. This used to happen to me all the time. Well, not with firearms, but with computers. I would increase the voltage and processor speed and things would get real good..... until some blue smoke with a funny smell escaped the processor. That was the magic. It had escaped! 😮

 

[Michael458]

Magic Powder?

Yes, absolutely true, I know there is such a thing, because I personally experienced ONE 5 lb keg of Magic RL 10X..................

Late in 2010 I was continuing load data for the mighty 500 MDM. .500 caliber, 2.8 inch RUM case. Test rifle is a 21 inch gun, and still working. At the time I opened a 5 lb Keg of RL 10X to give a go. I started getting results that was actually astounding, and hard to believe. But everything checked with the pressure reading across the board with every bullet tested. Bolt 0pened easy, brass measured within spec, no flat primers, absolutely all indicators agreed with the readings I was getting.

With this particular 5 lb of RL 10X I was pushing a 500 gr Solid with 102/RL 10X at 2617 fps 62700 PSI. 450 gr Solids with 105/RL 10X at 2758 fps 59400 PSI. And 375 gr North Forks 116/RL 10X at 3018 fps 62500 PSI.

At no point was there any indication of any issues along the way. And, it took 10-14 generations of test work to get to that point, so it was a gradual, tedious amount of test work. I was so confident in the findings that I published the data on the website. Fortunately I have always keep very close tabs on each of the 500 MDM rifles that were out in the world. There was not many at that time, and I had contact with everyone. Fortunately none of the guys had started any work with RL 10X by the time I burned that 5 lbs out, and started a new 5 lb Keg.

Another just pure luck, this keg was not as volatile as following ones. I loaded, tested, and got some pretty serious resistance on the bolt, out of spec measurements, and showing some serious signs of pressure. I was not hooked up at this point so I had no readings. ??????????????

Hookup and check time, I did, and I started out with much less of a charge this time to see what was going on. LONG STORY SHORT............ Working with 500 gr Solids I was only able to top out with 96/RL 10X and down to low 2500 fps before reaching 62000 PSI. It was a long way out from the first 5 lb Keg, down from 102 gr to max of 96 gr. This is not good, and could really be a major issue.

I pulled all the RL 10X data and discontinued use of RL 10X in 500 MDM after doing some more test work with other bullets discovering the same things. Immediately I pulled the data from the website, contacted 500 MDM owners and told them to NOT use any of those loads, and to not use RL 10X at all.

Later, another third 5 lb keg went even further, I was now down to 88/RL 10X for low 2400 fps and 62000 PSI. And it got worse with the next Keg and max load was 81/RL 10X.

Now imagine that I had published loading 102/RL 10X at 62000 with Keg #1. Now imagine someone having a keg of RL 10X like #3 or #4 where 81-88 gr was max! Yeah, me too............. Thank goodness I only have to imagine that.

Todays data we work with H-4895, IMR 8208 for top end velocity and pressures with that same 500 gr Solid and we get from 2350 fps to 2450 fps 61000 to 62500 PSI.

That was the only real honest to goodness Magic Powder that I have actually seen and experienced. But, that has not kept me from looking for it again. In fact, this very thought has caused me to attempt to create that Magic again in 500 MDM. I started blending different powders to see if I could find that Magic Powder, and reproduce it. I have blended different mixes of IMR 8208 with H-322, RL 10X. Blended RL 15 with H-322 and RL 7 and H-4198. And other combinations to investigate. Thus far I have NOT found the Magic Powder yet. I have been successful with one Blend however of 50% RL 15 and 50% RL 7 at least MATCHING the top end performance of stand alone loads with H-4895 and IMR 8208. I have been pleased with that, at least I can equal, but have not been able to exceed.

I have also searched for that Magic in other cartridges, small and large, and again, equal but not exceed results.......... And I managed to not blow anything up so far. LOL............

An example of one such Blended Trace.......

Also blended some for 500 Nitro Express, another example of that trace...........Also on this keep in mind top end pressures for 500 NE is 45000 PSI in Double Rifles.....

Always still looking for that MAGIC POWDER.....................

 

[Fess]

I have no doubt that there is occasionally a batch of powder that has just the right composition to perform extraordinarily well in a particular cartridge. Sometimes the variables just happen to hit some kind of synergistic peak point. I also have no doubt that there are some "hummer" barrels that are unusually accurate with a variety of loads. This stuff just happens, but not as frequently was we would like. I was just attempting to be funny.

Leverevolution is a good example of a powder that has just the right properties to seem magical in the 30-30, especially to those who traditionally loaded with IMR3031 or even Win 748. This time, however, the powder manufacturer knows how to consistently replicate the stuff.

 

[Michael458]

I was just attempting to be funny.

Good timing, allowed me to tell the story about magic powders....LOL....... I suspect from time to time I will get the itch to continue the search.............

One of the most challenging pressure projects I was ever involved with was for Christensen Arms and Superior Ammunition. Superior Ammunition headquarters is in Summerville SC. I have known the owner since he took over Superior many years ago and on occasion he gives me a call with some special projects he needs some help with. A few years ago Crhistensen Arms had requested that he load 200 rounds of "Proof Loads" for their 28 Nosler rifles. They requested a load that would produce 75000 PSI, and they were going to fire one round each in the new bolt guns they were going to produce. Lonnie calls me from Superior and requests that I help him with it, to which I agree of course. Never turn a shooter down when in need.

A week or so later Lonnie sends a new Christensen rifle up for it to be fitted with a strain gage and get it ready..........

Big mistake, Lonnie sent a "Carbon Wrapped Barrel" to start with......... I did not feel like that would work properly and give us proper readings.......... So I sent it back to him and then we got a all steel barrel rifle to work with.

I had of course on occasion had some loads that would hit in that 75000 PSI range by mistake, but I had never attempted to develop a 75000 PSI Load! This proved to be an extreme challenge. We quickly learned that things get really very very squirrely at 75000 PSI, the tiniest little nothing will throw things into chaos. At the time brass was being made from another Nosler cartridge, and there was some new 28 Nosler brass. We had to work with one or the other, but not mixed. Lonnie had brought a few boxes of 150 Barnes bullets, they were of different lot#s, and there was a difference in those pressures, just from one lot of bullets to the next, no measurable or visible differences in the bullets that we could detect.

We were up, and we were down, and trying to zero in on a steady, consistent 75000 PSI was more elusive than we could imagine. Our first tests went on for two days straight, and into the night! Then we ran out of damn bullets!

Tests were delayed for several days after that until Lonnie could get his hands on enough bullets, same lot#s. He needed enough to finalize the test work, and then enough on top of that to load the 200 rounds needed. Our best results and consistency was with 150 Nosler bullets, we just could not get enough consistency with the Barnes.

Once we started testing again, after 3 more days of grueling test work we finally had a consistent load. It was with the 150 Nosler and a heavy dose of H1000. It gave a very good and consistent 74800 PSI. We felt like this was close enough.

During this process we fired close to 150 rounds in the gun at anything from 68000 PSI up to 78900 PSI. Now, listen to this, NOT ONE TIME did we experience heavy bolt lift............. Brass showed wear and tear as normal. But the rifle never once told us this was too much pressure.

I would have to state that this was one hell of a good rifle. I cannot attest to anything such as accuracy as it was never fired past 25 yards. But I can attest to the fact that it held up fine after all those heavy loads and seemed to function like a champ. Too bad it was in a useless caliber, I might have kept it.......... I had it here for a month or more after the work before sending it back. Lonnie was able to give them the loads they requested and as far as I know everyone was happy from that point.

We ended up spending 5 full grueling days trying to accomplish this. It was not as simple as it seemed, and shooting at 75000 PSI + is squirrely at best..............

 

[ronn47]

@Michael458
What happens to the rifles chamber doing that type of load work up?
Does the steel get any type of work hardening like brass does?
What did the barrels throat look like after that many super hot loads thru it?
Thanks,
Ron

 

[Michael458]

What happens to the rifles chamber doing that type of load work up?
Does the steel get any type of work hardening like brass does?

Hi Ron............
Good question, I really don't have a reasonable or educated answer to. I don't think the chamber or steel gets a work hardening, at least not in the sense we think of with brass. I don't think steel is as elastic as brass
so I not sure it would get work hardened. I do know that you can push it too far and it will not come back to original size, massive over pressure. I did this once by mistake and according to Brian at SSK the receiver was
.003 out of spec, or I had stretched it that much. As I recall mind you, that has been some years back. Anyway, I do keep that receiver, Winchester M70, on the shelf as a reminder not to talk on the damn phone while making
up test loads!

Concerning this particular gun, and taking nearly 150 rounds of 70000 PSI + rounds, I did not measure or even look much at it. I did not have any regular ammo for it, so I did not shoot it anymore after we did the 28 Nosler proof loads
I don't believe it hurt the rifle any to be honest. One that can take that many over pressure loads, never have a heavy bolt lift, obviously is very precisely built. While anything over 65000 PSI is over Max pressure, this gun ate them up
like butter.

What did the barrels throat look like after that many super hot loads thru it?

Ron..... I never even looked down the barrel. I don't know.

Sorry, not much of an answer......

 

[Fess]

Mr. 458, you mentioned how smooth the action of the Christensen Arms rifle was even after massive abuse. Since you have worked with so many bolt action rifles, which models tend to have the smoothest actons? Do you need to go up into the custom actions, or are there a couple of less expensive brands that tend to be smooth. My reference is the Lee Enfield action, the only type of bolt action centerfire I have ever owned. Even the unissued No4 Mk2 that I once owned was very smooth, so it not just that most of them are well broken in. I am aware that part of the issue is that Lee Enfields half-cock on opening and half-cock on closing, which makes a normal bolt action feel weird to me.
Thanks

 

[Fess]

As for the problems with Barnes ammo. Small changes in composition of brass can have a significant impact on its in cold-working properties, what you would be seeing in the barrel. One batch of in-spec brass will have slightly different cold-forming and machining properties than the next. Years ago I worked in a factory that did a lot with brass. Cold-forming, machining and hot-heading. We had to use special lots of brass with a composition at the top end or bottom ends of some of the specs for everything to work properly. The normal variation of in-spec brass was too much for our equipment. Luckily we used 2 million pounds of the stuff annually, so the brass mills took the trouble to send us mainly the lots that met our more stringent specs.

edited to add: Modern brass bullets have grooves cut into the shank to reduce fouling and somewhat reduce variation in performance from lot to lot. The old Barnes solids with no grooves had more problems.

 

[Howland]

As for the problems with Barnes ammo. Small changes in composition of brass can have a significant impact on its in cold-working properties, what you would be seeing in the barrel. One batch of in-spec brass will have slightly different cold-forming and machining properties than the next. Years ago I worked in a factory that did a lot with brass. Cold-forming, machining and hot-heading. We had to use special lots of brass with a composition at the top end or bottom ends of some of the specs for everything to work properly. The normal variation of in-spec brass was too much for our equipment. Luckily we used 2 million pounds of the stuff annually, so the brass mills took the trouble to send us mainly the lots that met our more stringent specs.

I've been in exactly this situation. If memory serves me, the industry nomenclature for what we know as cartridge brass is C26000. Nominally it is 70% copper and 30% zinc, but I think the spec is +/- 1%, so it can be 69/31, 71/29 or anything in between. The properties vary more than just +/-1%. Much more. I know we had to do some "supplier quality development" and the foundry modified their processes for us. We also used tons.

I'm sure the companies that make cartridge brass also use tons. There is no telling whether some or any have tightened specs. I strongly suspect some do based on brands reputations for being relatively hard or soft. I would also bet that some just take standard brass.

 

[BatteryOaksBilly]

I would like to re-invite the new comers to our website....Just Google B&M Rifles and Cartridges ......the B is me and the M is Michael458. I think you will enjoy getting up to date on where this info comes from.

 

[Michael458]

Since you have worked with so many bolt action rifles, which models tend to have the smoothest actons?

I am personally extremely fond of Winchester M70s, and for the most part Control Feed versions. Nothing else is really of any serious interest. I have other bolt guns, most are dedicated test guns, or just holdovers from another time, but none of much consequence. When I go to the field with a bolt gun, it says Winchester on it.

As for the problems with Barnes ammo.

I assume you are talking about the issues mentioned in the 28 Nosler test. It was not ammunition, it was the actual 150 Barnes TSX or whatever it was. Take note, we were trying to get proof loads, not testing any sort of factory ammo. It was the Barnes bullets that were out of spec from one Lot# to the next, and we would have never even noticed those slight differences had we not been working above 70000 PSI. Under any normal circumstances, less than 65000 PSI any slight differences would have been inconsequential.

Brass did become a consideration, between New 28 Nosler, fired 28 Nosler, and I believe making 28 Nosler from another already established Nosler cartridge, maybe 26? I would have to look back at the data to make sure of that. There were big enough differences we had to pick one or the other throughout the tests, in the end I think we went with all New 28 Nosler brass. Which means would could not reload fired brass for testing. And of course various brass plays a very serious role with many cartridges, in particular the B&M cartridges which are based from RUM and WSM parents. Perhaps brass would be a good discussion for the next post on this little thread.....................

I think you will enjoy getting up to date on where this info comes from.

Not sure how much "up to date" anything much on the B&M website....... Since I retired from hunting, the search for proper designed bullets, and no more new B&M cartridges, I have become extremely lazy with keeping up with the site. I don't think I have added much to it in a few years now.........it desperately needs some up dating...............I have been saying that for some time now......


Moving on, back in December a fellow contacted me, I think he is from Texas, about some new bullets he is designing. He is having big visions and I won't go into all that, but he wanted me to test terminals for a bullet he has designed in .308 caliber, its a monolithic copper bullet with an aluminum tip. It weighs in at 152 gr. The only data he had was with 300 Winchester, but wanted some other velocities tested, and some very low velocity tested to give him an idea of how the bullet might behave at very low impact velocity. This week I loaded up a couple in 300 Winchester, 308 Winchester and 300 BLK for the low velocity tests.

Figured what the hell, test some pressures with the various loads just for giggles, and of course velocity, need that for the terminals to be done later, hopefully tomorrow. I hooked the 300 BLK up, only using the LabRadar unit I only got one velocity with 15/WW 296. Pressures were fine, but target velocity in the 1850 fps range was higher than desired for the test, I wanted 1600-1700 fps from the muzzle. Back to 13/WW 296 and got exactly what I wanted at 1680 fps and 43000 PSI. Easy.................

Next up was 308 Winchester. Using 44/IMR 8208 pressures were little higher than I would normally like in 308, at 58000 PSI. No velocity readings at all....... Damn, needed velocity more than pressure for this job.

Ended up cleaning up one of my PACT Pro Chronographs, setting it up as backup for the LabRadar. This should have been standard practice and has been in past more serious testing I have done. However, not having done extremely serious tests recently, I became extremely lazy. I had not yet tested the 300 Winchesters, need that velocity, so yesterday I set up one of the PACT Pros to get backup velocities.

Tested the PACT extensively on several different rifles and various Range ammo laying about. In every single instance I was able to get the backup velocities on every shot. Not so with the LabRadar, it would on occasion miss a shot or more. I felt confident now to test the 300 Win.

HEH........ Tested the only two rounds I had in 300 Winchester, and NEITHER the PACT or the damn LabRadar picked up the velocity!!!!!!!!!! ????????? It is an odd bullet, I can see why the LabRadar might miss it, STEALTH TECH... LOL I did get the Pressure with the 300 Winchester, but other than something to add to the data it really is of little consequence

The only bearing surface on the bullet is the high points you can see.......... The band below the top groove, and the very bottom where the larger middle groove starts..... Or that is how it measures, will most likely see the bearing surface in the terminal tests.........

 

[Fess]

I am sorry that I wasn't clear in my post about brass. I was talking about the bullets rather than the case. I don't know the exact composition of Barnes bullets, but I am fairly certain that they are one of the many types of brass rather than straight copper. Pure copper is gummy, fouls barrels rapidly and is miserable to machine. The cold forming I mentioned was the engraving of the bullet into the lands. As the bullet passes the throat, it is being swaged to the shape of the barrel interior. The material displaced by the lands needs to go somewhere. The old solid Barnes bullets essentially required swaging over the entire shank. Fired bullets were actually longer than unfired ones. Grooves cut into the shank of current brass bullets reduce the length that requires swaging and provide space for the material moved by the lands to go. The banded bullets you show are an extreme version of this, with the bands being just large enough for gas sealing and bullet orientation.

The factory I worked at made tire valves as well as other pneumatic components. These were the Schrader valves with the rubber exterior, rather than today's ones with tire pressure monitors. Schrader valves have a brass stem roughly the diameter and length of bullets. We got massive spools of brass and cold formed them into near-net-shape before final drilling, shaping and threading. The brass part that you screw the caps onto actually runs the full length of the valve stem, up to three inches long, depending on the model. The rubber is bonded to it.

 

[cold1]

I am sorry that I wasn't clear in my post about brass. I was talking about the bullets rather than the case. I don't know the exact composition of Barnes bullets, but I am fairly certain that they are one of the many types of brass rather than straight copper. Pure copper is gummy, fouls barrels rapidly and is miserable to machine. The cold forming I mentioned was the engraving of the bullet into the lands. As the bullet passes the throat, it is being swaged to the shape of the barrel interior. The material displaced by the lands needs to go somewhere. The old solid Barnes bullets essentially required swaging over the entire shank. Fired bullets were actually longer than unfired ones. Grooves cut into the shank of current brass bullets reduce the length that requires swaging and provide space for the material moved by the lands to go. The banded bullets you show are an extreme version of this, with the bands being just large enough for gas sealing and bullet orientation.

The factory I worked at made tire valves as well as other pneumatic components. These were the Schrader valves with the rubber exterior, rather than today's ones with tire pressure monitors. Schrader valves have a brass stem roughly the diameter and length of bullets. We got massive spools of brass and cold formed them into near-net-shape before final drilling, shaping and threading. The brass part that you screw the caps onto actually runs the full length of the valve stem, up to three inches long, depending on the model. The rubber is bonded to it.

I was enamored by those Barnes bullets when they came out. Huge hollow points for my 45-70. I got box and loaded up some marlin level rounds with them. I noticed after about 5 shots, my shots were drifting all over the target. I checked my barrel and found that the microgroove rifling was full of copper.

I think I pulled all the rounds down and threw away those Barnes bullets.

 

[Michael458]

I don't know the exact composition of Barnes bullets, but I am fairly certain that they are one of the many types of brass rather than straight copper. Pure copper is gummy, fouls barrels rapidly and is miserable to machine

Barnes is more copper than brass, not pure 100% copper, but have far more copper content. They are not brass, not any I know of anyway. I believe, not 100% sure, but I believe they are what is called either C101 or C110 Alloy. Yes, Copper is gummy as you say and more malleable than brass. This is why in the early days, (cold1 mentions this in his post above) that before they started cutting the grooves in the current TSX and similar bullets, they were full bearing surface. I tried several different calibers, cartridges, and rifles and accuracy was very poor and very inconsistent across the board. The minute they started cutting the grooves in the bullets via CNC, the Barnes became one of the most accurate hunting bullets you could get, I used them in several calibers and every rifle began to shoot great from that point forward. And still do. The grooves give that copper a place to go, or displace to, instead of smearing in the barrels. I still have a lot of those old barnes with no grooves, they were horrible. Terminals were great however, and that is the only reason I endeavored to use them.
The Cutting Edge Raptors and Solids that are brass is C360 Brass Alloy. The CEB Copper is a 99.5% Copper Alloy.

@cold1 , A few weeks ago I loaded some of those same older Barnes 45/70s for my guns, but they have the Ballard rifling not the Microgroove, and they actually shoot the things pretty good. The Barnes in the bigger bores always seemed to do a little better, I have shot some in 458 Win and 458 Lott without issue. I had a bunch of 300 gr Barnes .458s left over from years past, just loaded some and put them on the shelf. I have heard from other sources that the microgroove rifling did much the same as what you say.........

With any of the Monolithic bullets they need to have bands and or grooved to displace that metal........

This is the first example I can come across in copper, and may not be the best, but if you look to the bottom of the bands, you will see copper flowing past the band, into the groove cut, especially on the bottom band where copper flowed past the edge of the bottom of the band.................

On this copper bullet looking at the base on the left you will see copper flowing into the grooves above and below the bands........

Brass being a bit harder than copper does not flow as much as you can see here............Fairly sharp engraving.

 

[Fess]

It basically comes down to semantics. Our metal suppliers had dozens of copper alloys they called brass, including bronze, which also contains significant tin. If the copper alloy had zinc in it, they called it "brass". C260 (or 26000) alloy is often called cartridge brass and is a 70/30 copper/zinc composition. On the other hand, C210/C21000 is a 95/5 copper/zinc alloy has a distinct reddish tint. The C300/C30000-series brasses have lead in them which makes them machine much better than C200-series alloys. There are now some free-machining brasses that substitute bismuth for the lead that are used for making plumbing fixtures.

The pictures you posted do a really good job of showing the different coloration of the reddish high-copper-content bullet and the 70% copper/30% zinc brass case. The higher the zinc content, the "whiter" the color. You can see the tooling marks on those bullets and I bet they were a real pain to machine.

Part of the confusion is because Barnes initially did not want to use the phrase "brass bullets" for regulatory reasons. Brass bullets are forbidden for pistols in the Gun Control Act of 1968 where they are listed as being armor piercing. Barnes used the term "copper alloy" until they got an exemption. Technically brass IS a copper alloy.

 

[Michael458]

@Fess , I am far from a metallurgist expert and really can only speak about it in the broadest terms and in the terms of what I have tested here, both terminal and pressure.

Basically here we did not test different Alloys, it was simply Copper or Brass......... Knowing the brass was C360. We were interested in pressure differences in the two, but even more so in various band configurations and bearing surface. Then of particular interest in the terminal effects with the Solids. The Brass solids deformed much less on hard materials such as bone, than the same bullet in Copper. For the Raptors, the brass is more brittle, and one gets a more consistent shear of blades. But, later we also discovered through some manipulation and changes with the copper Raptors we could achieve the same results. Brass Raptors were just easier to get shear as long as the blades were not too thick on some of the larger bores.

Since this thread is dealing with pressures, one such test conducted here in 2010 was with .500 caliber 500 gr Solids. We had the original design with 8 bands with bearing surface. We wanted to reduce the number of bands, reducing pressures and barrel strain, but yet not be detrimental to accuracy or any other issues that might arise. The bullet we were working with was Brass........

We had CEB make the same bullet with 4 bands only.

This was a high pressure load, somewhat over max

The 8 Band bullet pressure averaged 67122 PSI

The 4 Band bullet pressure averaged 61265 PSI

Same exact bullet 8 Bands vs 4 Bands of bearing surface, Same load from the same keg of powder. Average was of two tests each, with 5 rounds each......

Nearly 6000 PSI less.

We also tested another bullet in Copper, and the results were basically the same.

We later tested 3 bands and then down to 2 bands only. There was very little difference between 2-4 bands in barrel strain and chamber pressures. 4 Bands with 3 located on the top, and one on the bottom worked best for various different cartridges, rifles and loading scenarios, so today from Cutting Edge, this is the band configuration you will see on all the Safari Solids and Raptors, and almost all those are brass.

With the same concept carried over to handgun, you will see all those are Copper.

I also worked with North Fork Technologies closely with the design of some of their bullets. North Fork normally has Micro Bands, a series of very tiny bands along the bearing surface. I had some larger runs of Solids done in .500, .458 and 416 calibers in which I changed the bands to two larger bands at the top, and a larger band at the bottom and the middle section retained the Micro bands. In this photo you will see also the Nose Profile Change to the newer more efficient angled nose, similar to the Cutting Edge BBW #13 nose profile............ The band configuration I did had no change at all in pressures or barrel strain over the straight Micro bands. But it did help with some loading practices especially when a crimp was needed. Other than that, I thought the new bands looked damn good............ LOL.............. All North Fork bullets are Copper. Company has since sold, and is now owned by a company in Sweden.

Below you see a sample of the 8 Band Brass vs the 4 Band Brass. For this test, the bands were even across the bullet, later the two middle bands would be moved up with the top band.

And here the Copper bullet test..........Also, moved those middle two bands up as well.

And Today here is the lineup of the Safari Solids available

 

[Fess]

Thank you for the information and the photos! It is not that often that we get to see different iterations of something during its design and testing process. I also think that your designs look better than the pure microband ones. In your testing, was there a significant difference in the pressure readings in going from something like the 8-band design to a 4-band design, or were there mainly other advantages?

My earlier point was just that bullet designers sometimes monkey with different alloys to get the performance they want and still be able to easily produce it. I would imagine that this was a big issue with the expanding mono-metal, monolithic, or lead-free bullets (or whatever a particular manufacturer calls them). In 2009, Hornady stated that they used Gilding Metal, a type of brass, in their GMX bullet line. That's where the product name came from. These days, they have switched to the term "copper alloy." My hat is off to the people who managed to figure out a material with a combination of properties that would reliably expand over a range of velocities and that cold be produced in large quantities for a reasonable price.

 

[Michael458]

In your testing, was there a significant difference in the pressure readings in going from something like the 8-band design to a 4-band design,

Hi Fess..... Yes, I suppose you missed it above, but if you go back and look at it there was 6000 PSI difference, of course with the 4 band version being less. 6000 PSI I would consider rather significant in this case, and no real difference in copper or brass versions, about the same, 6000 PSI.

I also think that your designs look better than the pure microband ones.

HEH... Yeah, me too! I hoard those, since I my close friend no longer owns North Fork Tech, I probably won't get anymore of those, and not sure anyone is getting any North Forks currently...... Glad I had enough done......

Thanks..........

Here are some of the very first copper solids that JD and I had Lehigh do about 12 years ago. These were, and they still are good bullets, but no "Tech" has been added to them except for the Flat Nose meplats. These could have been improved on greatly, however at that time Lehigh was not willing to do any research, so I started working with CEB and North Fork........

 

[Fess]

Hi Fess..... Yes, I suppose you missed it above, but if you go back and look at it there was 6000 PSI difference, of course with the 4 band version being less. 6000 PSI I would consider rather significant in this case, and no real difference in copper or brass versions, about the same, 6000 PSI.

Oops, some days my reading ain't so good.

 

[Fess]

I usually try to blame everything that goes wrong around here on my Wife's cats. It saves time. I am trying to think of some way I can blame my poor reading comprehension on them, but I haven't come up with anything yet.

 

[BatteryOaksBilly]

I usually try to blame everything that goes wrong around here on my Wife's cats. It saves time. I am trying to think of some way I can blame my poor reading comprehension on them, but I haven't come up with anything yet.

I got news.............................................it gets worse....73 and counting

 

[cold1]

I usually try to blame everything that goes wrong around here on my Wife's cats. It saves time. I am trying to think of some way I can blame my poor reading comprehension on them, but I haven't come up with anything yet.

Cat dander in your eyes making them tear up while reading.

Just trying to help 😉

 

[Michael458]

My apologies up front, this post is a repeat of the post on 45/70 and questions about using Unique. I thought it relevant to this thread in particular, and then a continuation after that with some observations to share...............

Copied from the other thread...........


think it was the end of last week I finally got around to checking that strain gage. After removing the protective tape it was indeed loose and had lost its bond. No wonder, I don't understand why I chose that damn gun to begin with, it had engraving under the gage and bond, and was sure to loose bond at some point....... Oh well.....

I chose another gun, I have 4 of these things laying around currently anyway. I added the strain gage, let it sit for 24 hours, then taped over it to protect it and it sit for probably another 3-4 days curing. I decided today was the day to revisit this, my curiosity peaked..... But first, we had to check the strain gage connection to make sure it was good, and on top of that we had to check a known load to see how it compared with past tests.

This will be the third Marlin set up with strain gage and tested.

The old standby Load is 405 Remington with 40/IMR 4198.

From my data I see I tested this load on 12/21/2005 and at that time it gave 1615 fps at 32600 PSI.
Another gun, tested on 8/22/2014 it gave1540 fps at 28600 PSI. Both Velocity and Pressure lower than the 2005 test, but still within 4000 PSI, which is acceptable, especially considering velocity matches the lower pressure given.
Now, today, yet a different gun and new strain gage the same load gives 1621 fps at 30100 PSI. Well within spec.

This is 3 different guns, span of 15 plus years, different brass, primers, powder..... yeah, I would say well within reason and spec. I feel more than confident we are getting good readings.

Now, on to the question at hand, that peaked my curiosity...............

Chihuahua Floyd said:
Can 45-70 be loaded with Red Dot or Unique?

I tried a 405 Remington with 15/Unique a couple of weeks ago. Very light load, showed no real pressures, and tested at 1109 fps in the other gun.

Today, in the different rifle, now connected with a proper gage we get 1122 fps and 25600 PSI average. While the velocity gave a very low ES (Extreme Spread) the ES for pressures was not good at 3700 PSI. This is not acceptable to me.

I went up to 405 Remington with 17/Unique for 1230 fps at 31200 PSI. ES was stupid good with velocity, and a little better with 2800 PSI on pressures.

Rules of Pressure...... #1 Rule WEIGHT EQUAL PRESSURE

I dropped the bullet weight down and tested a 300 Remington HP

Using 17/Unique with the 300 Rem HP we get 1335 fps at 21700 PSI ES was 2200 PSI

Moving up to 20/Unique 300 Rem HP we get 1517 fps at 28600 PSI ES 2600 PSI.

I will accept the larger ES for PSI for these light loads, normally when they top over 2000 PSI ES I start looking at them harder... but for these type of loads not really sure it makes much difference. What is crazy is the ES for velocity is stupid low on all of them........ They would appear to be great loads if that is all you looked at.......... I suppose they are plenty good enough, if they meet your Pressure parameters......

I believe some thing was mentioned about pressures for TrapDoor guns? I really do not know what the upper end is for those weaker guns, since I never dealt with any personally....... Just a quick search as I type this I see 21000 PSI mentioned on one search, and 28000 PSI mentioned for modern replicas........ Before you shoot yours, make sure you know...........Knowing this, I would probably stay with the lighter bullets......... especially with Unique.

 

[Michael458]

Now continuing on with 45/70 since we are back up and running there are several things I want to look at.

In the previous post we looked at Unique, which is certainly not a common 45/70 powder. I had mentioned on that thread that for years on top of years I had used 28/IMR 4198 with about any bullet you can imagine for very light, low pressure and low velocity loads. In looking up data, I did not actually have any pressure data on that load. I knew it was very light, and never really saw a reason to actually test. Well, today was the day that was explored somewhat and put to rest....

I only tested Two bullets

400 Cast no Gas Check 28/IMR 4198 1146 fps at 17600 PSI

405 Remington 28/IMR 4198 1068 fps at 11700 PSI or less...... I say or LESS, because this is the bottom threshold of where the Oehler 83 measures pressures, of 3 rounds fired, this was probably the highest reading, the other two did not even register. I would either have to reset the Oehler, or move to the RSI unit, which I might do later for some other things as well..............

Pressures would even be much lower with lighter bullets....... 28/IMR 4198 is a very light load, and very low pressures. The Cast bullet is most likely bigger diameter, .459 and hence the increase of pressure over the 405 Remington. This is a guess, I actually have not measured yet, I am moving on to another project in 45/70 with 225 and 250 Lehigh Extreme Penetrators............