My 357 magnum which is on the sb1 frame is reamed for the max and I've had no problems after several hundred rounds through it. I think if there is a problem it is the sb1 frame will shoot loose sooner than a sb2 frame but the question is how many thousands of rounds does that take. the difference in SAAMI pressure between the two is not all that great....35,000 vs 40,000. Just my opinion.