FWIW, I've used thousands of Rem. 7-1/2's over the years...starting in the '90's when they were about the only thing that would hang in there on the .17 Remingtons and other big cased .17's I was working with. Eventually, bushing the firing pin hole and profiling the pit tip got ahead of those issues to where any quality, thicker cupped SR primer was viable.
Though I've heard them referred to as Magnums, I've never seen any 7-1/2's actually labeled as such from Remington.
Good shootin'. -Al
