Not sure where to put this - Data from the range today

KnotRight

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When to the range today to find out what was the chamber length in the 308, 6.5 CM and bolt action 223.

Using a set of Hornady headspace gauges and a digital caliper.

The 308 brass started out with an average of 1.5948"
After firing the average was 1.6182"
Difference of 0.0234"
I was shooting 40.4 grns of Varget under a 168 gn bullet (?)
The book velocity stated 2500 and I was getting 2530



The 6.5 CM brass started out with an average of 1.5535"
After firing the average was 1.5566"
Difference of 0.0031"

The 223 brass started out with an average of 1.4503"
After firing the average was 1.4514"
Difference of 0.0011"
I was shooting 26.2 grns of CFE223 under a 62 gn Hornady FMY and the book velocity was 3000
I was only getting an average of 2680

Where would you set the shoulder bump on your dies with those differences?

The only gun that I shot @ 100 yards was the 308 because I am not having the results that I used to get. After a few adjustments on the scope I was getting every shot straight up and down (less than 1" from left to right) but the top shot was 2.5" above the bottom shot.
What do you think is causing that type of pattern?
 
With AR platform rifles, just pop the upper off, find your longest case at the shoulder, insert it under the extractor and slide the BCG forward with just your finger. If it goes to bolt lock up with just light finger pressure, your cases haven't fully expanded yet. If it won't lock up, just turn your die down bit by bit until it locks with just finger pressure. Your 14 tpi die threads will set the shoulder back almost exactly .001" with a 5° turn. I use a sharpie to mark the die and a compass to measure how much I'm turning.

As for the vertical stringing, I think you would know if it was velocity variation because you said you were running a chrono. Not sure where to point you on that question.
 
As for the vertical stringing, I think you would know if it was velocity variation because you said you were running a chrono. Not sure where to point you on that question.

Howland, I was getting way too much SD on the velocity. The chrono that I am using is not the best out there (Chrono F-1). Not sure why the SD because I trim the brass and trickle the charges when I load the 308 and 6.5 CM. I am using the Hornady digital scale (not the low end one) to weight the powder. And before I start to load, I will turn on the scale maybe 1/2 of an hour before I use it and recalibrate it. I am wondering how much the brass comes into play with the SD.
 
How old or how may times has your brass been fired? Is it all the same brand of brass? Do you anneal? All of these factors can affect your ES/SD.
 
How high of SD is "way too much?" SD calculated from groups of five can be unhelpful.

I'm working up a load in .338LM. Accuracy is a very modest load at the low end of the powder charge range. ES was horrible on seating depth testing until the deepest seating depth. My theory is that there wasn't enough neck tension and I wasn't getting consistent ignition. Now I have to try different bushings and mandrels. The point is, your issues could be anything. The powder/bullet combination might not be ideal or just a combination your rifle doesn't like, but the powder you listed for .308 & .223 aren't oddball choices. How tightly are you controlling seating depth? Match primers? Are you verifying charge weights on a balance beam scale? There are many possible reasons.
 
When to the range today to find out what was the chamber length in the 308, 6.5 CM and bolt action 223.

Using a set of Hornady headspace gauges and a digital caliper.

The 308 brass started out with an average of 1.5948"
After firing the average was 1.6182"
Difference of 0.0234"
I was shooting 40.4 grns of Varget under a 168 gn bullet (?)
The book velocity stated 2500 and I was getting 2530



The 6.5 CM brass started out with an average of 1.5535"
After firing the average was 1.5566"
Difference of 0.0031"

The 223 brass started out with an average of 1.4503"
After firing the average was 1.4514"
Difference of 0.0011"
I was shooting 26.2 grns of CFE223 under a 62 gn Hornady FMY and the book velocity was 3000
I was only getting an average of 2680

Where would you set the shoulder bump on your dies with those differences?

The only gun that I shot @ 100 yards was the 308 because I am not having the results that I used to get. After a few adjustments on the scope I was getting every shot straight up and down (less than 1" from left to right) but the top shot was 2.5" above the bottom shot.
What do you think is causing that type of pattern?

As posted in the other topic, the stringing is your breath stroke
 
I just resized all the brass that was shot today and set the die to where it was touching the shell holder and then backed off about a turn. Worked one piece of brass until it was completely flush with the Wilson case gauge. Then did another and it too was flush. Then measured the brass and it was the same. I am working to make sure all the brass is the same size.

Ncav8tor, I do not anneal the brass (but thought about doing a salt water annealing). The brass is on it 3 or 4 firing. I do try to keep the brand of brass the same in lots of 20. About a year ago, I posted something about having the neck too short and effecting the accuracy. Now that I got the dies locked into, I am going back and making sure the trimming (WFT) is set correctly since it works off the shoulder of the brass. And I do not think that the rabbit hole ever ends.

Howland, I checked the digital scale with a set of RCBS weights and it was dead on it.

As I mention in one of the threads I was using a Chrono F-1. I really need to verify the accuracy of it against a couple other chrono. What brand of chronos are you using. Would love the LabRadar but it is out of my price range.
 
Nothing wrong with the F1 Chrony, IMHO. Just make sure it is far enough out front so the muzzle blast won't affect the readings. (True with any optical chrono).

For determining the proper shoulder setback, I do basically the same procedure as @Howland mentioned, except I use the Redding competition shell holders to control my setback.

For me, annealing did help some, but not a lot, for reducing SD and ES. What did make a big difference was when I also started neck turning. Having all the necks annealed the same amount AND the same wall thickness apparently made for very consistent neck tension. Also, in the testing I did, crimping increased the SD and ES dramatically. After I tested for bullet setback or jump with uncrimped rounds (tested by manually feeding multiple times, and measuring the OAL) I now don't crimp any of my AR rounds that I load for precision - the neck tension alone is enough to hold them. I still put a light crimp on the plinking rounds, though.

Even doing all that, sometimes a particular bullet/OAL/brass/powder/primer/rifle combo may not yield low extreme spreads.

I use the salt-bath method for annealing. If I did greater quantities of brass, though, I would probably go with the Annealeeze.
 
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