Question about uneven wear on bolt's lug faces

[SDW]

Ah, good idea. And I happen to have a set of Hornady headspace comparators arriving in the same box with the Upper lapping tool. They'll come in handy for that. I can use it right away to check my fired brass against my reloaded ammunition; see how badly my Lee FL resizing die screwed them up. LOL

FWIW, I am planning to get a Forster FL sizer and bullet seater before doing any more Grendel reloading.