What is acceptable rifling?|Page 2|Restoration, Repair and Maintenance|Forum|Winchester Collector

Well, there are more ways for the bolt to rotate than I had thought of.  When the bolt is not locked forward, the links have a bit of play.  If a broken X or a bent Y or a crusted Z, then you’ve found the problem.

Instead of listing possibilities here (and because I am not a gunsmith though I do play one on TV,) I’ll wait to hear of your discoveries when you look inside your ’76.