I have a pre-ban Eagle Arms/Armalite A2 16" upper with a stainless steel barrel, threaded for flash hider.  The barrel outside dimensions are as follows: Under handguards = 0.875", At front sight = 0.750" & In front of sight = 0.720".  The barrel markings are: SS, W & 1/9.
My question is, does anyone know if this barrel would have been chambered NATO 556mm, or SAMMI .223?  My understanding is that "modern" stainless steel barrels are usually HBARs or bull dimentioned and would be chambered SAMMI for accuracy. I e-mailed Eagle Arms, but have not yet recieved any reply.  By the way, thanks to all for a great forum!

I have found it doesn't really matter if the chamber is SAAMI or NATO.

Thanks, guys for the input.  I will be contacting Kurt regarding re-chambering to 556mm.  I do intend to be using the NATO M193/Q3131 loads and I do not want to be taking a chance w/ stuck brass (even for range trips).

Harry, I've had my Pre Ban Eagle Arms for about eight years now.  I've shot about 4,000 rounds of surplus 5.56mm through it and have NEVER had a casing get stuck in the chamber.  Just food for thought.

Dan

I have shot a lot of Q3131a without problem.  Also Lake City, and other NATO ammo.  I DON'T shoot Wolf.

Your Eagle Arms is mfg'd by Armalite.  Go to www.armalite.com and on the left in the blue field click on Tech Notes.  Then read Tech Note 45.  That should be helpful.

Just had to revitalize this thread because I just got off the phone with someone at Armalite.

The lady I spoke with said it really doesn't matter what the chamber is.  They claim that millions of NATO spec ammo has been fired through SAAMI chambers without a problem.  

I really hope this is true.  I hope to have an older Eagle Arms Predator in my hands in the next couple of weeks.  
Scott

This tread reminded me that there was something I needed to look up..

I had seen reference to a [blue][b].223 Wylde[/b][/blue] chamber in some of the ads in SGN, mostly for the flattop "accuracy" type uppers/bbl's.

Well, seems there are quite a few chambers along the .223 / 5.56 topic...

check this link out, just to make things even more confusing: [:)]

[url]http://www.radomski.us/njhp/cart_tech.htm[/url]

If you shoot surplus, you'd want Nato chambering.  I had one lot of SA surplus that would not function 100% in a Ruger or Model 1 upper but the stuff works 100% in a Colt barrel.