Originally Posted by
Tannhauser
I realize I am resurrecting an old post, but I found this thread incredibly informative and useful.
I recently entered into the 10mm world with a S&W M&P 10mm with a 4.6” barrel. I’ve been working up loads, and this thread popped up in my Google searches.
I was looking for information on loading heavy hardcast in 10mm, but what really jumped out at me was the failures documented by the author are almost exactly what sone M&P10mm owners are reporting when shooting Undereood or Buffalo Bore 200 and 220 hardcast - namely, failures yo feed and mags ones dropping free.
I’ve only been shooting 180 gr JHP handloads, and even with almost max charges of Blue Dot and I have no failures over a couple hundred rounds.
I replaced my factory recoil assembly with a 22# Wolff recoil spring almost immediately, because it seemed these lightweight pistols were under-sprung from the factory.
I think the users shooting stock recoil Springs, stock magazine Springs with heavy hardcast loads are experiencing problems due to slide velocity and frame flex.