CHUCK, So you're saying the saw and the a2 have different chambers than each other? or you mean they're different than .223. I do know this, I've got brass that I saved from black hills and then from all the other manufactures I've shot. Black hills uses nato brass. Obviously commercial ones don't. If you put the two side by side the nato stamped brass is clearly longer than any of the saami .223 stuff I've shot. That being remington, winchester, pmc, umc, hornady and I think that's it. So, I'm not necessarily disagreeing with you but It's not all adding up. But people obviosly shoot the black hills in bolt guns so it must fit but at the same time the black hills is loaded to saami pressures. So you're dealing with 2 entities, chamber and pressure. Now you said that the saw and the a2 have diferent chambers altogether but if they're bigger wouldn't they be considered 5.56 chambers? So, I'm not sure where the joke is I'm just trying to figure it out and what you're saying is a lot different than what alot of other people said. If you go to the winchester ammo sight, you can access the ranger ammunition sight which is the law enforcement ammo. It also states there that the chambers are different. You may be right but I'm just going by what some of the "experts" are saying. jj out