Is there an appreciable difference within 20-30 yards?
Tim McMurray who owns MAC1 probably knows more about air rifles than most and he believes that the .177 is for precision target shooting and the .22 is for field use. He is an advocate of heavy pellets to maximize kinetic energy transfer on live targets.
If you shot 'em in the head either will do, but for body shots the .22 with heavy pellets is preferable.
www.mac1airgunshop.comEDIT: I have a couple of old S&W 77As, a 55 year old Crosman 1400 series,an equally old Crosman 622 CO2 rifle that looks like it could be a Remington 760 understudy, and a 40-odd year old Sheridan that might be called a Blue Streak. The 77A are nice, man-sized, pellet guns that have been through a MAC1 rebuild. They are pretty accurate and kill opossums, rabbits, and squirrels without much noise.
