"owned"?? .22 rifle at the age of 16 which now belongs to my son. First handgun and shotgun at the age of 22. Didn't consider myself a late starter though since I could "borrow" rifles or shotguns from friends or relatives at a much earlier age. My son has owned guns earlier than I did but only had access to them when I was with him until a later age (they were all locked and I had the keys).
There is a difference between owning a gun and really "owning" a gun.