Decided to start another thread instead of keeping it off topic in the beehive round thread. Anyway, as I mentioned I think the problem with ProMags Mini 14 mags is the thickness of the front and back walls are causing drag problems with longer rounds. I loaded a factory and a ProMag with three rounds of the same 55 gr Sierra Ballistic tips. If you look very close at the photo you can see more space between the front of the rounds in the Ruger mag. In the ProMag you can not even slip a thin sheet of spiral notebook paper between the nose of the bullet and front of the magazine.
I also have the feeling the Mini 14 GB is designed to function correctly with the higher pressure 5.56 round and not the 223 round. That will be my next experiment.
I also have the feeling the Mini 14 GB is designed to function correctly with the higher pressure 5.56 round and not the 223 round. That will be my next experiment.