I have a m70 Coyote with a 9 twist bbl that has over 11,000 rounds down it, mostly 40 gr Vmax with 28 grains of H335 in Win brass.
I had it punched .223AI a couple years ago and it continues to shoot well with 40's right at 4,000 fps.
It will blow up some of the thinner jacketed bullets such as the Hornady 50 gr SX's and the Sierra 50 gr Blitz bullets.
The throat is cracked for 6" or so according to a local smith with a Hawkeye fwiw.
