New Pmags Fit, old ones don't
So i've got a Double Star lower on my latest build, and i've got six Pmags that I've had for about three years, and none of them will seat in the gun like they should. You gotta put some serious testicles behind it to get these suckers to seat. Well I bought a few new Pmags, and they all fit absolutely perfect, and seat exactly like they should. So my question is why would old Pmags not fit a gun that new Pmags will fit perfectly? Am I just absolutely retarded? Any kinda explanation would be appreciated.
Pmags have changed slightly since their introduction.
You can lightly sand on the older magazine bodies to get them to fit your receiver. Just look for the areas where it rubs and remove a bit of plastic with sand paper.
The newer version Pmags must have been designed with slightly smaller/thinner areas in the body to fit the wide variety of lower receivers.
My experience has been that if the older Pmag doesn't quite fit the lower receiver, the lower receiver is made slightly off of spec. Not enough to give trouble with USGI magazines, but just enough to cause fit issues with Pmags.