The Brass Weight Theory

Discussion in 'Reloading' started by Downeast, Jul 11, 2019.

  1. Downeast

    Downeast Happy to be here

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    I purchased 100 rounds of brand new Hornady brass (6mm CM) the other day and weighed it out just for the sake of curiosity. The range of weight was +/- 5 grains. I then sorted out 50 pieces of brass with a range of +/- 1 grain. The remaining brass I call the "variable weight" lot, ranging from 2-5 grains difference. I'm going to load 10 rounds with the +/- 1 grain brass and 10 random rounds of the "variable weight" brass. I expect that the spread of the variable weight brass will be greater than the +/- 1 grain due to difference in case capacity and pressure. I've heard stories and read numerous articles about the importance of weighing brass for accuracy but I have never seen anyone actually test the concept. To make it easier to see variation (spread size) I'm going to shoot at 500 yards.

    I imagine that there is a youtube video floating around out there somewhere but I'm wondering if any of you have done this? I'm always looking for an excuse to burn powder. :D
     
  2. Tim

    Tim I am....an enchanter. Staff Member Benefactor Charter Life Member

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    At least I HOPE my edits prove true....I stopped keeping track of # of loads for brass, weighing brass, truing meplats, sorting bullets by weight (i.e. I don't care if my "140s" are 141 or 142) and all of that minutiae some time ago. Accuracy has not suffered at all. I do check cases for split necks and other damage, but otherwise just toss empties in a bin, tumble and reload as needed.

    My unsubstantiated claim is that so long as you're in the sweet spot of a node for your barrel, all of that other stuff is just OCD fodder.
     
    Last edited: Jul 11, 2019
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  3. Downeast

    Downeast Happy to be here

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    What do you consider "accuracy"?
     
  4. Tim

    Tim I am....an enchanter. Staff Member Benefactor Charter Life Member

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    Sub 3/4 MOA confirmed to 750 yards.
     
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  5. Michael458

    Michael458 Active Member

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    Let me first say, shooting rat guns, and shooting 500 yards is way way out of my area of expertise.

    But, loading and pressures fall within some of my area...... I don't think a variable of 3-5 grains in case weight is going to make much of a difference, when considering there are other variables involved too. If one was shooting serious heavy benchrest, maybe... again, out of my area of expertise........... Common shooting, no, you would be hard pressed to see. Pressures, no, not 5 grains difference in brass weight.

    But, here is something to ponder, but it deals with far far more differences in weight. Today I had to get a 458 B&M ready for a fellow in Louisiana. Basically just check his rifle to make sure feed/function is good, and load a few rounds and send with the gun. He is a pig shooter, and likes to bust the hell out of them. I am loading a 250 Socom from CEB 77/H-4198. A 458 B&M is a 2.240 inch RUM case. Cut, trim to 2.240 and size to .458 caliber. Rifle is a 18 inch Winchester M70 WSM action.

    When the cartridges were first developed in 2005 there was ONLY Remington brass available, so everything was based on that case. Today you can't get any Remington RUM. You have Hornady, Nosler and Norma making RUM Brass today. There is a huge difference in weight and capacity of these different pieces.

    Remington RUM weighs in at 240 grains, Nosler/Norma at 260 grains, and Hornady is thinner, lighter at 230 grains. These are big differences. I ended up having to test pressures with these and to make sure all of it worked in the various B&Ms.......

    The test work was with 450 Grain CEB Solids 76/TAC.

    Remington Brass

    2276 fps at 60500 PSI

    Norma Brass

    2287 fps at 58500 PSI

    Nosler Brass

    2305 fps at 58800 PSI.

    Hornady Brass

    2220 fps at 52000 PSI

    Weight of the case is basically capacity. The Hornady brass being much lighter, thinner, more capacity, so more internal volume, and less pressure and velocity. The Remington, Nosler, and Norma are all heavier, less internal case capacity, more pressure, more velocity with the same loads. I tested the Hornady brass, it will hold 65000 PSI, but you have to up your powder charge with the Hornady to equal velocity and pressures of
    the other brass. Not a big deal, but just a bit aggravating if you are looking for top end performance. I do not do that in most cases, believe me, a 450 CEB Solid at 2220 fps is plenty, and will go from end to end on buffalo
    and more than enough for elephant and hippo at any angle. 2275-2300 however does drive deeper, and hits harder........

    Today I shot the 250 Socoms, with 77/H-4198. Remington brass was 2940 fps, Hornady brass at 2920 fps and Nosler brass came to 2968 fps. Not really a huge difference and this is big bore as well, so it is not near as finicky as smaller bore cartridges.

    Probably not really related to what you are trying to do, but just to point out that while most of the time there are so many other factors involved, that 5 gr difference in case weight would not make a difference to me, not in big bores. But those tiny rat shooters are finicky, so test it and find out for yourself. Forget what the so called "Experts have to say"..... I find they don't know near as much as they think they do, thats why I do it myself and find out the truth..........

    BTW, 50 yards is a LONG LONG LONG way for me! HEH.... Hell I can't see anything past 50 yards, so I damn sure can't shoot it further........
     
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  6. Downeast

    Downeast Happy to be here

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    Thanks Michael for the reply. It's nice to see numbers. Cool.

    So Tim, you are shooting a group a bit below 6 inches at 750 yards with different bullet weights, different brass, etc? That is awesome and pretty well turns the world of handloading upside down.
     
  7. Tim

    Tim I am....an enchanter. Staff Member Benefactor Charter Life Member

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    I am able to consistently hit 7" plate at 750 on a calm day. So, I'll amend to "just under MOA".

    When loading I do pay close attention to powder charge, seating depth, crimp (or lack of crimp, depending), etc. I do use same brand of brass, so I'm not mixing Hornady and Lapua for example.

    So it's not like I'm just eyeballing things.
     
    Last edited: Jul 11, 2019
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  8. JimB

    JimB Picking it up slowly. Benefactor Charter Life Member

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    I you’re going to weigh brass, consider doing it after all the the brass prep. Not hard to take off a few grains deburring a flash hole, uniforming a primer picket and trimming to length after sizing. Can’t say that any of it matters, but if you’re gonna be compulsive, then be compulsive.
     
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  9. Sharps40

    Sharps40 Price, it's all about the price

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    Amen!
     
  10. Sharps40

    Sharps40 Price, it's all about the price

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    With an average rifle at averade ranges say under300 yds i agree with sweetspot

    For any gun at extreme range and especially a high end gun....control every variable you can at the loading bench.

    Most of us are the former and we often seem to unnecessarily apply effort to a rifle much less capable of shooting to the potential of highly taylored handloads. But. Its fun to talk up your load anyway!!
     
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  11. Tim

    Tim I am....an enchanter. Staff Member Benefactor Charter Life Member

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    I think the object is to ensure case volume uniformity, resulting in more consistent pressures.

    If you're trimming case length it doesn't impact cartridge base to ogive and therefore shouldn't impact case volume. If you're deburring or swaging primer pockets, same thing.

    Each of those processes impacts case weight without impacting case volume. So I don't see how brass weight impacts the end result.
     
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  12. Tim

    Tim I am....an enchanter. Staff Member Benefactor Charter Life Member

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    Crimp and jump to lands (cartridge base to ogive) both play a more important role in consistent pressure than brass weight in my completely amateur and unscientific opinion.
     
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  13. Downeast

    Downeast Happy to be here

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    Heat index right now is 108 degrees (hopefully F and not C!) so I'm fooling around in the reloading room. That's why started weighing some new brass and found the weight discrepancies. Fun stuff to ponder over and a good excuse to burn some powder. On a good day I can hit a 4 inch plate every time at 400 yards, and about half the time at 600 yards with both my 6 and 6.5 CM. But I'm really enjoying handloading and shooting the 6 Creedmoor. I found some 600 yard benchrest targets (blue colored rings) the other day and we're thinking of having a match sometime soon. We keep putting it off due to range construction and the damn weather!

    The 600 yard target size is 1.2" for the "x", 2.8" for the 10 ring, 5.2" for the 9, down to 10" for the 7 ring and 14.8" for the 5 ring. That should make our beer swilling gang perk up. :eek:
     
  14. JimB

    JimB Picking it up slowly. Benefactor Charter Life Member

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    I think that you’re reasoning is right, but your conclusion is wrong. Because these variables affect case weight, but not case volume, you need to eliminate them in order to accurately use case weight as a proxy for case volume. For example, take two identical cases and then trim one to length. By weight you’d think the trimmed one had less volume because it weighs less, but obviously it does not.
     
  15. Tim

    Tim I am....an enchanter. Staff Member Benefactor Charter Life Member

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    Given what you said, we'd need to begin taking number of firings and previous trimmings into consideration. As a case is fired, the brass can flow from the body to the neck and will then be trimmed back...so 2 cases of equal length (and we could assume equal primer pocket dimensions) may have different weights as the walls thin out. Which is, of course, why many/most meticulous reloaded will track firings. I.e. Your "weight as proxy for volume" which was a much more succinct way of putting it.

    Since brevity is the soul of wit, I suspect you are more right than I am.

    My contention is not that any of this is false...I contend that it just doesn't matter enough to bother. As usual, I admit that I am as likely as not to be wrong. It will be interesting to see the OP's results.
     
    Last edited: Jul 11, 2019
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  16. Smack

    Smack Member

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    From what I have experienced in the past, starting with all the same brass, necks trimmed having all the same thickness, annealing, bushing die for right amount of tension, and bench rest primers, are a must for repeated accuracy in long range
     
    Last edited: Jul 12, 2019
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  17. Toprudder

    Toprudder Be vewy vewy qwiet. Supporting Member

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    It all adds up. Just how much do you need to do? Depends. I did not see much improvement with annealing (but I was mainly expecting annealing to improve the life of the brass anyway). What really surprised me was how much the standard deviation improved with turning the necks. Who knew that consistent neck wall thickness would result in consistent neck tension. :) Of course, all of this has very little effect at 100 yards, but really shows up at 600.
     
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  18. Smack

    Smack Member

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    With out annealing my brass would spring back after 4 to 5 firings from being hardened,
    never giving me consistent neck tension, the brass would actually squeal going through my
    dies no matter how much lube I used, wore out a few die bushings until I started annealing
    after every other firing.

    My groups and ES also shrink when I use bench rest primers, guys like to deburr primer holes to get an even flame
    but if the primer flame isn't consistent you get ES.

    Like you said, it all shows up at 600, and even at 300 depending on the caliber, but at 100 its not worth all the time,
    we like to shoot at dumdum suckers at 100, then after shooting the candy we try for the stick.

    In the end its just great being out with friends !
     
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  19. Toprudder

    Toprudder Be vewy vewy qwiet. Supporting Member

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    I don't have any brass with that many firings (yet).

    Yep! :)