So I measured some pull down brass from the new 350 Legend Brass which holds 35.5 Grains H2O. Formed a couple into Bottlenecks and came up with 33 Grains Powder capacity. So with a .380" Shoulder near 1.71" Length this Brass might appeal to some Shooters. This is basically long 9mm Brass with rebated Rim of the .223. I hope this is the Correct Forum, if not please remove. 3rd time's the Charm.