On my Rem 700 based 300 PRC I'm using Hawkins M5 CIP-length bottom metal and CIP-length AICs, 300RUM mags. No feeding issues - none what-so-ever.
I am going to run this as well.
I do not like the magazine release on the PTG. I know some guys trim it down, which kind of supports my thoughts. The Seekins has a button out of the way which I like. The Hawkins has a push tab that is clean and out of the way as well. Both to me are much better thought out and designed.
Seekins
Hawkins