Grendel mags?

[pinzgauer]

Pinz, I thinned the walls on the pmag -inside.- Side to side-front to back

Interesting, that must have been challenging! did you use a long mill to do so? trying to think how someone could do that on a 30 rounder.

I think the trick on the feed lips would be to heat and reshape rather than grind. You really don't want them thinner. I may take a grendel dummy round and see what a heat gun will do to the feed lips. Can't go too high or it will hit the bolt carrier I'm thinking.

For cold weather I'd be looking at something like rhinoliner on the mag body if that was a concern. (just the part that sticks out the mag well)