If I'm out of the badlands (shortgrass prairie) or working along the butte tops, I prefer .30-06 for deer--much better at those ranges, although my favorite rifle for that work has a scope on a tip-off mount and iron sights in case I decide to work the bottoms and don't want to switch rifles.
While my son-in-law has taken quite a few deer with the .30-30, I never bought one for some reason.
I don't think it would be fun to shoot out of a handgun, and yes, I have shot T/Cs before. I reckon the light loads would make a difference, though.
I was very favorably impressed with the accuracy and muzzle velocity developed with the T/C Encore using the 15" 460 barrel. I fired a .454 Casull 200 gr round at one of my steel spinners. It nearly punched all the way through the 3/8" steel. The same load in the Ruger Super Redhawk just made a moonscape of the spinner. Clearly, the 15" barrel provided additional velocity. I now have a 20" 460 barrel to place on the T/C Encore. That should be a very fine rifle and capable of 45LC, .454 Casull and 460 S&W mag.