I'm asking because I saw somewhere that some ARs can't withstand the pressure from the round. Ever heard of this?

YES! YES! YES!But dont think it was a pressure problem, I do reload some of my loads way hotter(long range) than that stuff. I also have a bunch of Norico(yellow box)stuff thats hotter than Q3131a. I Chrono

I have only had experience with the Q3131 and have been pleased with both reliability and decent accuracy.

I'll let you know. I have 1000 rounds of Q3131A on the way plus 1200 rounds of IMI SS109 Green Tip. Should be here sometime next week. I read the comments in the Ammo Forum on all the different brands, etc. Check that out. Very good info there.

The only problem I can recall ever having with Q3131A is not having enough!  The stuff is accurate, dependable and reasonably inexpensive (from [url]www.ammoman.com[/url]).  If I had to pick one thing that may be a negative about Q3131A, it would be the significant muzzle flash from my post-ban (no flash hider)carbine.  Other than that, no complaints.

I've purchased a few lots of Q3131A from a few different places.  It has all shot well.  It is on my list as my "standard" ammo - i.e. ammo of choice.   It's as close to mil spec Lake City that you can get IMHO.

I think the pressure thing you're talking about has something to do with SAMMI (stands for Standards and Measurements something or other . . )    

I guess SAMMI rated certain rifles chambers capable of withstanding higher or lower cartridge pressures.  They distinguished between .223 commercial rifles and rounds intended for these rifles and mil spec 5.56mm rifles and rounds intended for them.   Of course, 5.56mm and .223 is the same caliber, but my understanding was that 5.56 is a military designation for a higher performing (pressure, velocity) round.

Can't remember if this was how it all went, but I think Troy wrote it somewhere on the old board about 1.5 or more  years ago when he was moderating the ammo section.

BTW - the conclusion was if you've got Colt, BM, DPMS, Armalite then you are ok to shoot the 5.56 high pressure stuff.