I have a Marlin Cowboy in 45 Colt and in this area of Kansas it makes a very good Deer rifle.
I hand load using Marlin data as listed in the reloading manuals. I prefer hard cast bullets with gas checks. LBT's work best for me.
Buffalo Bore,Garrett and Cor-bon make good loads although a bit pricey.
The new 45 case is fine, have never split one.
Rifle or carbine really brings out the best in this cartridge.