308 Winchester.

I love my Ruger Mark II bolt action, and it has proven it's worth in the field. This gun has shot aprox 12 deer between me and a friend who has borrowed it and out of these only one deer has moved any distance after being shot, and that was my fault in bullet placement, that deer made it aprox 40 yards before he died. Most just seem to fall over. I usually use 150 grain bullets and currently shoot Winchester Supreme's in 150 grain.