I have been thinking about loading 190grSMK to shoot in my Springfield M1A(service grade). I have read that this heavy of a bullet is hard on a gas gun because of increased port pressure. The operating rod is reputed to bend or break.

I am trying to comprehend how a 150 gr bullet charged with 47gr of RL-15, producing 50,000 CUP would have lower port pressure than a 190 gr bullet charged with only 42 gr of RL-15 and producing only 47,500 CUP.

The load/pressure data is from Hodgdon#26.

Can somebody "turn on the light" for me.

Thanks, MM

In Hornady's 5th edition, a 178 grain bullet is the heavest bullet listed in their M1A section. It lists 41.0 grains of RL-15 as the max load.

Maybe www.fulton-armory.com can help

I'm not so sure that you would have to worry about port pressure as much as recoil impulse in youe M1A. I have been shootint Garands for a few years & know that you can damage the op rods by using the wrong (read slow burning) powders. The pressure may actualing be the same but the curve is different (so I've read). I think the it's sim. as you move up to longer projectiles. Just a thought.