So the Pmag you used was the 10/5 round "stubby" - correct?
Yes.
I got them from Blaxsun here on CGN. I need to get another myself, I don't know what I was smoking on my first attempt. But I put my 10rd'r on backwards. By that time the JB weld had already hardened and I broke the lips off of the Pmag trying to to fix my mistake by taking the OEM mag off