I just bought a Winchester model 70 in 7mm magnum and have been at the range shooting. I have zeroed in at 225 yards and am shooting 2" groups. I do not reload and am shooting Remington Core Lokt 150 gr. ptd. soft point bullets. They seem to shoot very accurate but is this bullet weight heavy enough for trophy bulls? If not, what grain should I be shooting. Thanks, and Merry Christmas!