If you do not already have one I would suggest a clone of a Peacemaker 45 colt.
I've had one for over three years. Mine is a Cimarron Artillery model 5 1/2" barrel in 45 colt. I'm 52. I've been shooting since I was five and have several types of rifles, shotguns, and handguns. The Cimarron has become my most fun gun. I've just recently acquired a Rossi 92 lever action rifle that will arrive next week for my birthday.
You can get a Peacemaker clone in 22 caliber also.
We all wanted to be cowboys... so get some cowboy guns and have fun.
Strive to live up to the opinion that your dog has of you.