Be careful in Colorado, they now have a limit on the number of cartridges you can have in a magazine and the number the magazine can take.
You will likely be persecuted to the full extent of the law and then some.
A .44 Special +p load (265 grain flat nose at 900 ft per second) should do everything you need it to, Garret had one available at one time and Buffalo Bore may have one.
If you are going to use a Glock, make sure it is downloaded vis a vis the number of cartridges in the mag. if you are going to Colorado.
A 1911 with a standard mag and the Buffalo Bore 255 grain +p (make sure they work) should suffice if you can't bring your Glock because of mag restrictions.
You much more likely to run into human predator scum than a bear, angry deer or crazed elk.
Aggressive dogs and stupid owners can be problem too.
They make 15 round mags for glock 20s. He ahould be ok. Here in Jersey we have the same capacity limit