Chuck; No was not referring to you. I can see a distinct possibility of pattern improvment brought about from less deformed shot. I believe you are right about the presure at muzzle. Of course the wt of the powder charge determines the weight of gases exiting, which plays a part s well as the exit velocity. Of course if we could actually determine the exact exit velocity for any individual shot we could exactly figure recoil. Generally speaking the higher the CWR, the slower the burn rate of the powder will have to be to maintain acceptable chamber pressures, therefore the higher will be the muzzle pressure. The .30 cal magnum even with the 150gr bullet would normally burn a slower powder as well as have a much smaller expansion ratio than would a .458 mag with a 500 gr bullet, thus would likely have a higher muzzle pressure. The 500 grain buillet is 3.333 times heavier than the 150gr, but would have a similar wt powder charge, so the percentage of the recoil from the exiting gases is a smaller proportion of the total recoil. Those guns which have the highest percentage of their rcoil produced by the exiting gases reap the largest benefits from muzzle brakes/porting etc. They also of course produce the largest increase in side blast.
