I've been a dedicated handgun hunter for quite a few years now. My primary hunting gun was a scoped 9.5" Ruger Super Redhawk. I went with a 2-6x Bushnell scope sighted in at 100 yards. I've taken several deer with this handgun, with the farthest shot being about 75 yards. I like the scope, especially where I may have shots out to 100 yards or so.
I also hunt with an iron sighted 7.5" Ruger Super Blackhawk for when my shots will be around 50 yards or so. I have shot this handgun at 100 yards and have no doubt I can hit a deer-sized target at that distance, but I use the SBH when hunting thick, brushy areas where 50 yards would be a long shot.
A .44 Magnum in a decent barrel length handgun has plenty of punch at 100 yards to take down a deer.