I would have zero reservations about shooting at a deer out to 100yds with my 5.5" Ruger. I don't shoot full power ammo most of the time either, 245 SWC at 1175fps. With practice and a rest I've shot 4" groups for 6 shots at the 100 yard line. Though the bullet won't be going too fast when it gets there, I'd bet there isn't a whitetail around that could stop it on a broadside shot. I've killed a decent sized bear and one big hog with this gun and load, both times the shot angle has been steep and I've got 3' or more of penetration along with an exit.
For deer I'd think almost any factory load would work, I've never been to where you hunt but I doubt the deer are any bigger or tougher than they are where I've hunted. A buddy of mine killed a pretty big grizzly with one shot from his 5" 629 a few years ago. His load of choice, Winchester white box 240 soft point, one shot to the chest folded him up from about 25 yards.
