Swapped to a different barrel - 1 in 9 (Colt, I believe - may have to take another look) so which ammo should I get?   Nothing quickly found in the Armory or Ar-15 forums.  I thought there was an ammo forum, no?

Are you fukkin' kidding me?

All I can muster.... is a

Thanks for all your valuable help, guys.  PRK out.

Quoted: Just giving you hell because it really doesn't matter. Anybody who says any different doesn't know what they are talking about.

What doesnt matter????  Ammy types in barrels?  It damned sure does.  And there IS an ammo forum, and the FAQ's clearly cover this.... and the guy has been a member since 2001 and cant search, find the ammo forums, etc????

Sorry, this whole thread stinks.

Take both rounds and compare them with your calipers. What do you see?

you talking about the www.ammo-oracle.com/?

Quoted: 5.56 is shot in .223 guns every day and you never hear of any problems. Regardless of the pressure exceeding SAAMI specs nobody's gun ever blows up. It doesn't matter...

Sorry - you are flat wrong on this.  I have had an AR with a .223 chamber.  When I fired 5,56 ammo in it.... I had all kinds of extraction issues, and popped primers like crazy, from Q3131A and South African.  I was ripping the side of the rim off on many rounds.  Yet, the gun ran fine on cheap .223 ammo.

I was a newbie - had no clue what was going on.... came to this site, and found out, that what I was experiencing is the exact problem you have when you shoot high pressure 5.56 in a .223 SAAMI chamber.

This is because of the higher pressure.  Period.  I am not saying it is unsafe.... I cant speak to that.  But I can tell you the likelihood of having extraction and primer issues increases greatly when firing 5.56 in a .223 chamber.... huh.... just like the Ammo Oracle tells us.