Actually, there are several states that allow buckshot for deer, including PA in some areas, so single projectile is not a moot point. The word shotgun has a meaning, the fact that ammo was made to allow a shotgun shoot single projectile ammo doesn't change that. However, a rifled barreld gun that is made to shoot cartridges with bullets instead of rifled slugs could very easily beconsidered a rifle, not a shotgun, even though it is designated by gauge instead of caliber. Some states could well consider a 24 gauge gun a rifle if it has a rifled barrel when using a metalic or plastic casing and loaded with a bullet instead of a rifled slug which is the case here if I understood what I read. I have alreaded sent an e-mail to the PGC to see what their interpretation is on it for our state.