For backpacking, personally, I'd go with a smith and wesson 625 Mountain Gun. Stainless steel with a 4 inch barrel and 6 rounds of .45 colt. Not the most powerful round, but will knock down damn near anything you need it to in the U.S.
It used to, I was not a real big fan of it however.
How is the recoil on your .44sp Mountain Gun?This is what I carry for bumming around the woods, a S&W Model 396 Mountain Lite in .44 Special. It weighs 18 oz empty, has a 3-3/8" barrel, and can shoot lead bullets, jacketed hollow points, or home-made shot shells. It's been discontinued by S&W, but is usually available on either Gunsamerica or Gunbroker. When carrying this thing, I usually forget it's there on my hip. Loaded with five rounds, plus another five in a speedloader in my pocket, and I'm reasonably prepared for just about anything.
So you are backpacking without a hip belt on your pack? How much does your pack typically weigh? That must kill ya by the end of the 20th mile in a day. If you are strong enough to carry 30 pounds on your back with out a hip belt, then I guess you probably can carry whatever gun you want!