[220combat]

The 45-70 is not available in a handgun. I would stick with the 44Mag or 45Colt. The 44-40 is a fine cartridge, but if you don't handload, it will be expensive to buy and hard to find. A 44 or 45 carbine woudl make a fine defensive weapon, inexpensive plinker, and a capable deer rifle at shorter ranges. I have a Rossi carbine in 45 colt, and it is a fine shooter. It is top eject, and some of the shells do hit me while ejecting, but it's no big deal.

 

[220combat]

The 45-70 is available in a pistol.
I own the Magnum Research 45-70 revolver.
I do know you can get a Thompson Contender barrel too.

You're right, but those 2 guns are quite specialty guns, and not ones that come to mind when you think of handgun cartridges.

 

[220combat]

THe 336 model (and variants) are only offered in the rifle calibers You have to go to the Marlin 1894 model (and variants) to get the handgun calibers, but they are top eject. The Mossberg gun only comes in 30-30 at the moment, but it is side eject like the 336.

The Marlin costs a couple hundred more than the Rossi, but the fit and finish are better. The Rossi also has an odd safety, mounted on the top of the bolt.