What is the smallest caliber rifle you have or have seen anyone take a deer with? When I was a kid, an old farmer I knew used to get out to his barn real early and shoot deer that came into his apple orchard behind the barn. He used a .22 (sometimes with shorts) and used to pop them through the eye at a range of about 20 to 30 feet. I don't recall any of them needing a second shot. Good thing too since he only had a single shot rifle. Can't remember the brand but it was a bolt action and you had to pull a knurled knob out to cock it.