TedBrewer5 Wrote:So it is a design issue with the feed ramp/ramp divider?.
You could say that. There are no dedicated Grendel barrel extensions that I am aware of. The shape of the two feed channels on extensions are designed for 223/5.56, which of course is a narrower case. There are posts on the Forum talking about widening the feed ramps with a Dremel to make for smoother feeding into the chamber.
In your case it may be an easier fix to play with the mag lips. Once you shave the channels it is permanent (so it better make things better). Maybe even include polishing the underside and edges of the lip that is causing the trouble. The deal is, the mag needs to release the cartridge more freely in your case, so it pops up earlier and presents more parallel to the chamber. The more it grips the case the more it gets pushed up and presents at an angle with the BCG ramming it into the knife edge.
That should fix it, but if it doesn't then a different brand of magazine might work.