Mags came with the gun, some unmarked so unknown manufacture, some are a product of the manufacture. Im not ready to out the gun maker yet but maybe soon.
Some brass scaring yes, seems that the angle of the feed ramp to chamber may be to steep and catch's the round in the top of the mag, kind of pinching it. If the bolt is pulled back slightly then sent forward again the round goes home fine. Also very little tolerance on the distance from the nose of the round to the base of the feed ramp. Rounds have to be fully set to the rear of the mag or the nose of the round catches on the base of the feed ramp and its a no go on chambering.
Not much I can do on round length, using 168gr federal's.
Gunna try new mags before milling down the angle of the feed ramp.