pumpgun and Dr. Howell: Thanks for your very helpful comments.

I was hoping to be able to take game such as deer or wild hogs with a scoped Thompson Center pistol with 15" barrel at ranges of over 200 yards. Are 250 to 300-yard shots feasible with , say, a .308 from a 15" barrel? Would they be feasible with the .444 Marlin or a (handloaded) 45-70, from that gun?