Brass weight discrepancies

[Lenny Foffa]

Great thread, I have asked this question as well. My Winchester cases in .270 Win can go from 186.0 to 189.9. I separate by .3 Grain. Remington cases all seem to run 190.0 to 195 .0 and Nosler brass is even heavier . My Load is fairly hot, 59.5 Grns H 4831 , and seems to fill the the case about 96%.to 98% and the Nolser 130 Grn Ballistic Tips seat deeply into the neck of the case, for a 3.340 COAL . My personal rule is to drop down to my accuracy load which is 59.2 Grns H 4831 as cases get heavier. My question is still in cases that weigh over 190 Grns , should Reduce the load even more??? I see that if internal case volume is the same , then the reduction in powder may not be necessary .

 

[jfolanddvm]

So, to assume that because brass weighs more, it has to have less volume, would also require the assumption that the material those cases were made from had exactly the same density. More dense components could result in a heavier case with exactly the same internal and external dimensions. The only way to know for sure, as stated would be to do a capacity test.
Now for my stupid question of the day - I assume you are measuring the water/isopropyl alcohol after resizing the cases, so what do you use to plug the primer pocket? In these times, I'm not even really wanting to burn one primer to do the test!

 

[QuietTexan]

Either leave the fired primer in the case, use a 21st Century plug, or one guy here was saying he uses the same fired primer cup minus the anvil to the same effect as the plugs.

Primer Pocket Plugs

21st Century Shooting, Primer Pocket Plugs

www.xxicsi.com

I would weigh before sizing. In regards to sorting cases the actual volume is less important than minimal variance from case to case. If you were using volume to develop loads in QL or something along those lines then yes the specific volume is very important.

 

[LongBomber]

I don't know that sorting a batch of lapua, adg or alpha brass is worth doing. But with those I have not seen more than a 1.5ish grain variance over a 100-200 case batch in the same production run.
But with bulk bag remington or winchester brass I have seen a 12-15gr variation in 100 cases. That much change will make a difference and warrants sorting. When weighing the bulk bags of brass it looks like brass from multiple production lines is mixed. You get weights centered on 2-3 points, which at least makes sorting into batches simple.

 

[MagnumManiac]

I will add this to the discussion.
Just because one brand is heavier than another DOES NOT mean you can assume a capacity difference.
For example, I run 7RM brass in my 264WM rifles because I can no longer buy loaded rounds or loose 264WM brass by any maker.
I also have old correctly head stamped brass by Remington and Winchester.
They weigh within 5 grains of each other, yet the Remington holds much less powder than the Winchester brass….the reason is that the internal dimensions are vastly different. The Winchester has a very thick web, .050"", the case walls are thinner. The Remington brass has a web of .035" and thicker walls that stay thicker much higher in the case.
The 300WM brass I have is the same. Brass weight does not necessarily mean less or more capacity, unless you actually measure it, you are guessing at best.
Another thing, you should only take measurements off brass that has been fired 3 times with only being neck sized, otherwise the results will not be a true representation.

Cheers.