Jake,
I weighed all the brass from 3 different lots (boxes loaded ammo) of 300 Ultra Mag brass I had after they were fired, nothing else done to them either. All 60 cases were + or - .2gr (two tenth gr)in water capacity from the average, BUT, all the cases themselves were spread out over a four grain weight range! Needless to say, the variation on the inside is not indicated well by the cases initial weight at all. Time will tell how long they hold up. I have not even bothered to weigh the 100 rd bag of bulk brass I bought yet. They've all been prept and trimmed etc, so it's too late to compare them now. I figured if three seperate lots of loaded ammo came out that close I'd do ok with the 100 round bag. After 3 loadings now, I have a couple marked cases that were a little looser than normal seating primers but still fine, we'll see how they are next time. I just turned the necks down to .014" last week to even them up, other than that no complaints with these ones. I have had problems with them in the past in 308win loosing the primer pockets faster and splitting necks but never really used them much after switching to winchester stuff. Case capacities on win. seemed to be more consistant than federal stuff was so I steered clear of it too. The federal or winchester seems to last a bit longer without annealing necks at all, but they're life is all reduced if you don't do that, so now I do it to all of them every three or four loadings.