Hey I just got my order from Model 1, 16" bull barrel upper.   I already know they messed up my order cause they gave me a stainless barrel instead of what finish I ordered but whatever.  I was just wondering if there is any way to determine whether it is chambered .223 or 5.56 mm like I ordered.  I'm sure everyone who's ordered from model 1 knows that it says "M1S" on the barrel but is there any other indicator, because I think if I call them they will just tell me whatever they feel like.  

Well i can say that if you got a stainless you got a deal since they charge more for the SS then they do a standard, but you also more then likely got a .223 chamber and not a 5.56.... When  got my upper from them, it was what i ordered except for the chamber size. Someone posted that they send the .223 as a default size unless stated otherwise, but since they already messed up your order with the wrong finish, its likely the chamber is wrong as well.....

hmm ok well thanks a lot model 1!