Your friend in all honesty should not be talking about things like this. A .22lr(pretty sure this is what he was talking about) at 1 mile would MAYBE have enough energy behind it to make you realize you were hit by it. .45 auto, .45 long colt, and 45-70 would have the same amount of energy at a mile.
At the velocities that these rounds have they would be coming straight down on top of your head too at that distance pretty much. If you are hit by anything at a mile you will either barely notice that you were hit by it or it would feel like being hit by a paintball. a .308 barely has the power at 1 mile to be lethal and that round is good at long distances. The effective range on a .308 is really only rated to 900 yards(half a mile pretty much). The only thing you will have to worry about at a mile would be .338 lapua magnum, and .50 bmg. A mile is one hell of a distance that most rounds can’t make let alone shooters can make. I have made a 1 mile shot(actually was 100 yards over a mile), and the only other people who I have met that have ever successfully had a 1 mile+ shot were ex military or people who have been shooting for years and are in their 50’s.
For a person a .22lr has an effective range of probably 400 yards, .45 depending on which one you are talking about would generally be the same if not less… Again though these rounds have pretty horrible ballistics so if you were hit by one at a mile you would be hit in the top of the head unless you were laying down for some reason.