Quote Originally Posted by joeg26er View Post
Brand of bolt catch?
It was a cheap generic bolt release.

Quote Originally Posted by Dr. Bullseye View Post
The way I read this, you tested each variable separately. This is the way to trouble shoot any problem. The only problem resulted in the use of Pmags, either generation. On the other hand USGI did work. Shouldn't you be looking a those pmags more closely?
Pmags and GI mags interface with the bolt catch differently. When the catch is damaged or becomes misaligned, often one type of mag will work while another will be problematic.