I would also do a whole hearted '.44 mag' vote. I'll add one more wrinkle too.
What if they don't like it? What if they do like the challange, but want more, and go with a bow? What if they can't hit squat with a big hand gun?
It is much easier to unload (sell) a .44 mag gun/holster/ammo then a more esoteric single shot type gun. I know we love 'em, and drool over them, but the #1 stolen car is the Toyota Carola (or was, might trade with the Civic). Why? It is easy to unload. You are more likely to get a greater percentage of your investment out of a s/w 629 or Ruger Super Blackhawk than a single shot. More likely to be able to sell it to a co-worker and not have to wholesale it.

I'm sure any gun listed here, if the shooter does his part, will bring in that first handgun kill. But I also know I missed my first deer (5 times, it climed the tree and dope slapped me, and I still missed it), but kept at it, and love it.
My s/w 29 6" is still my favorite gun for anything except swimming.

Dogsbreath