Purely my experience and results but I shot well over 900 rounds of Hornady 40 Vmax thru my 14.5" 7 twist AR in 2 1/2 day, without cleaning, and the only blowups I encountered was on the prairie dogs.All shooting was done suppressed and there were some times when the barrel got so hot it melted part of the interior of the old ranch truck we were riding in.I have a 7 twist 22br and I need a bullet for pdogs. I'm concerned that 77gr tmk/ 80 Bergers are too large of a grain bullet for varmints. Any ideas are greatly appreciated? Spin rate is also a conundrum?