differences in construction of mixed GI brass

[Kurastduuks]

Hey there, haven't been on in a looooooong time (life got CRAZY), but need some input from THR. I recently made a trade I'm pretty pleased with (acquired a rem 700 308, shilen 20" barrel, mcrees precision aluminum side folding chassis, harris bipod). My only 308 brass I've got laying around is mixed once-fired GI surplus (LC, WCC, IMI) I used to load for my M1A and while I will undoubtedly eventually pick up some premium brass for this rifle like I do with other precision rifles I was curious and began working up a load in the mixed brass. At 4X.00gr of 4064 with 168gr hornady BTHP match bullets, federal match primers, and uniformed brass (again mixed headstamps) my last 5 shot group of the day measured just a hair under a .5" @ 110 yrds. When I initially started loading this brass for my M1A I did a water test of the internal volumes of the cases but have no idea where the notebook is I documented my results in.
So my question is, before I chronograph this load to see if it actually has a decent enough ES/SD to stick with (and maybe save myself from buying more nosler or lapua brass) has anyone out there checked to see the capacity/dimensional variances of NATO spec/NATO stamped brass made by different manufacturers?

 

[Kaldor]

I have not, but I do know that my commercial brass I can load a little hotter on my 308. That being said, I only use LC 7.62 brass, which I automatically drop down 2gr from book max and work up. I would assume being that WCC and IMI are milspec, I would hazard a guess that they are similar.

 

[macgrumpy]

Older military brass (LC) was pretty consistent at around 53 to 54 grains of water capacity but I've seen newer lots of LC brass go as high as 55.5gr of water (my Lapua brass averages around 56 grains). I suspect that the newer military long range ammo that was built by ATK uses brass that is closer to the higher quality commercial brass and that would explain some of the higher capacities. Recently I've used a case capacity of 55.5r for my QuickLoad estimates and my muzzle velocity estimates usually come out to within 30fps of my chronograph averages.

 

[Kurastduuks]

Well got out yesterday with the chronograph, put 10 rounds through it averaging 2622 with a 4fps standard deviation so guess I'll just keep loading that big pile of free brass thats been sitting in the drawer forever! Group opened up a bit to .75 but thats probably just me, I'm a happy camper.