We buy our brass in bulk, and have just prepped a sack that had 1,449 cases.

We size them all, debur the flash hole, uniform the primer pockets, and trim.

After this we weigh them to separate each lot within 1 grain.

1 case was 89.8
25 cases were in the 90 range
446 cases were in the 91 range
583 cases were in the 92 range
377 cases were in the 93 range
17 cases were in the 94 range.

We have a brand new Steyer Mannlicher Varmint Pro rifle, in 223.

It is a different one to the one that had the silencer.

I am going to develop loads for it, and thought of trying something.

I will select 10 cases of exactly the same weight, and I will select 10 cases of varying weights across all the weights posted above.

I will shoot the same loads in both, and see if there is any difference in the results.

Any guesses of what might we get??

Will you be starting with a fouled barrel?
Will you be cleaning the rifle during the testing?
Will you somehow control or measure barrel temperature during the test?
Do you have an idea what bullet you will use?
My guess is you will get better repeatability with the homogenous lot but both lots can be MOA or not.

Anxious to see your results!!! rioger

Even if you have a top notch shooter behind the trigger, it's gonna be hard to tell. And you'll need to repeat the cycle several times to see if your findings are valid.
While I'm not much on weighing cases, when I am setting up my match brass, I fire cull the cases. Often it will take several firings before I settle on the final batch of brass even though I start out with pre-prepped brass.
Even though I use brass that is already prepped and weighed, I'm gonna guess that it ain't going to make much difference depending on whether you're shooting varmints or competitive targets.

Hard to say but it will be interesting to see and I appreciate you doing these tests as it may dispel a few commonly held beliefs about what really impacts accuracy.

I am glad you had time to weight the cases.

Personally I just load them and shoot them.

quote:

Originally posted by sep:
Hard to say but it will be interesting to see and I appreciate you doing these tests as it may dispel a few commonly held beliefs about what really impacts accuracy.

+1

I'll bet a you will not see a repeatable measurable difference.

Looking forward to seeing the results.

It ain't going to make any difference.

quote:

Originally posted by ramrod340:
I'll bet a you will not see a repeatable measurable difference.

Looking forward to seeing the results.

I'll take that bet! roger

quote:

I'll take that bet!

Don't start betting yet.

The rifle we originally had for this test has been borrowed.

So we have decided to use a Remington PSS HB instead.

I have already shot two powders, but will not post the results until I am done.

And for those who use the Oehler Model 35P chronograph, you might remember how often one has to change the paper roll.

We buy ours in a larger roll made for office calculators.

Trouble is that roll is too big to fit into the Oehler.

So what we have been doing is rolling our own rolls to fit the Oehler.

A normal roll makes almost 5 rolls to fit in.

Yesterday we ran out of rolls made small enough to fit the chronograph, and I thought of making a modification so that I can fit a bigger roll on it.

I found two small steel plates from a light fitting, that seem to fit our purpose.

I used super glue to glue these on either side of the chronograph, and found a suitable size screw and nut, and we had it done.

It does not look pretty, but sure makes a difference.

Will take a photo and post it later.

The small roll is the normal size that fits into the chronograph.

Now I can use the original, larger roll.

Unless the shooter is unaware of which ammunition he is using a prejudice can be introduced which will make the results questionable.

I'm thinking bullet runout will have more effect than case weights. Will you only shoot loaded rounds with 0.003" or less of indicated runout?

I have never tested any of our loads for bullet runout.

Nice rigging of the printer paper supply.

Not a bad batch of brass.

1406 out of 1449 pieces are about 92 grains weight each piece, +/- 1 grain, roughly speaking, to 1 grain level.

I have never seen a lot of correlation between case weight and internal case capacity:
Is it less or more brass in the case that causes the weight variation,
or is it lesser or greater density of the brass that is there in each case?
Maybe more of the former than of the latter, but some compensating errors are possible there.

I am going to hazard a guess that there won't be any statistically significant difference between the two lots of brass that Saeed has proposed to test ...
As long as Walter is not involved in any aspect of the testing.

OK let me see if I have this right. Brass is 8.7 times more dense than water. So if you "assume" that the weight difference between the cases is ONLY caused by internal volumes. Meaning that the outside dimension and length are exactly the same.

So ignoring the bottom case to keep it simple there is a 4 gr difference from min to max. Now divide that by the difference in density 4/8.7 then you get a .4598 grs of water difference. Now divide that by the 28.8grs of water capacity of the 223. .4598/28.8 = .016 or a 1.6% difference in case capacity.

Now to keep it simple take QL with a 55gr bullet and vary the capacity by the full .4598 to give the max capacity difference. Min volume is 3259fps and max is 3231fps "calculated" . For a difference potential to volume of 28fps or .86%

You are a better shot and have a much better rifle than I have to be able tie a group difference to this capacity change.

Heck toss the 17 heavy cases and you are down to a 1.2% or about 18fps.

Well, here are the results, and as everyone seems to have guessed, not much of a difference.

Black is with brass of exactly the same weight.

Red is with brass that had a maximum weight difference of 4 grains.

quote:

Originally posted by ramrod340:

quote:

I'll take that bet!

I O U roger

Let me know next time you are in Denver.

quote:

Originally posted by ramrod340:
Let me know next time you are in Denver.

If you wait till I get to Denver it ain't gonna happen. I can no longer breath up that high.

Guess you'll just have to come to LA. roger

quote:

If you wait till I get to Denver it ain't gonna happen. I can no longer breath up that high.Guess you'll just have to come to LA.

yep air does get a touch thin. As to me in LA will never happen.

So I guess we caulk this up to you owe me one and we will leave it on account until the next time I disagree with you and are wrong. Will probably happen this week.

I raise my to you as I type.

Saeed,

You should build a bench rest rifle and compete for a while in the States...then it would be interesting to see what you decide is "important" when it comes to getting consistent 0.1" 5 shot groups.

quote:

Originally posted by Ackley Improved User:
Saeed,

You should build a bench rest rifle and compete for a while in the States...then it would be interesting to see what you decide is "important" when it comes to getting consistent 0.1" 5 shot groups.

I think there a lot of rifles that are capable of shooting like that and better.

Trouble is with reading the wind, and unless I am shooting at animal, I am terrible at reading it