For the sake of clarity: My main character is going to be shot in the chest from across a room (15 feet max). The character who's doing the shooting expecting to demonstrably hurt, but not kill, him. Bruising, maiming, the bigger the better, so long as it won't kill him. Preferably, it should tear his clothing as well, but that's not strictly necessary.
All forms of tranquilizer guns are out, but, other than that, neither cost nor expertise (in using or knowing to use the weapon) is prohibitive.
EDIT: I should point out that there is absolutely no chance of the character actually dying, since he's bulletproof, and that the character who's doing the shooting has no intention of actually killing him.
SON OF EDIT: Thanks, everybody! Looks like I'm going to go with plastic/acrylic bullets.