jackh:
What do you mean by spc and spcii ammo?! There's no such thing. Commercial ammo is typically safe for shooting out of the spc and spcII chambers.
For your upper, if it's not marked on the barrel, then most likely a SPC chamber (original SAAMI chambering produced by Remington and the like). Where did you get the barrel/upper from?
Additionally, the upper, if it is a SPC chamber, will not be safe for shooting "Tactical" loads from SSA, or handloaded to max levels. Obviously, if you do reload start at the minimum, and work up until swipes start appearing, or other pressure signs start becoming apparent.
WHat is the box of "SpcII" ammo you're talking about?
