After the discussion in other threads about the cases for .223 military brass being thicker, and thus producing lesser volume in the cases, requiring smaller loads, I decided to take some brass apart and see what was what. I think you'll be surprised at what I found. I was. Five brass casings: R P 223 Rem, FC 08, Winchester .223 Rem, FC 223 Rem, and LC 04. Hopefully this will come through well--sometimes tables don't work so well in posts. First. after depriming and trimming to length, here are the weights, in grains, of the five cases: RP223Rem: 91.5 gr FC 08: 92.1 Winchester .223 Rem: 96.3 FC 223 Rem: 91.5 LC 04: 92.3. The heaviest casing was, oddly, the commercial Winchester brass I just bought last week and fired once. Second, I cut off the necks, producing a "cartridge" 1.25" long. After removing the burr, I then used a dial caliper to determine casing wall thickness at that length : RP223Rem: .012" FC 08: .012-.013" Winchester ..223 Rem: .012-.013" FC 223 Rem: .013-.014" LC 04: .012-.013" Then, I cut the cartridges down again, leaving them 1/2" long. I measured the casing wall again at that length, after removing any burrs: RP223Rem: .027" FC 08: .025" Winchester .223 Rem: .030" FC 223 Rem: .025" LC 04: .027" What's the upshot of all this? The conventional wisdom is that military cases are thicker, resulting in a smaller volume within the case which will, for the same amount of powder, produce higher pressures. But what I see is that the commercial cartridge casing, the Winchester, is the thickest of all, resulting in the smallest volume w/in the casing.! Can anyone shed some light on this? Obviously, the samples are small, but shockingly different than what we'd expect if the conventional wisdom is true. It sure looks to me like there isn't all that much difference between the cartirdges. (And yes, I did one of each kind, not a large sample).