If i want to put a pistol grip (just a pistol grip...not a pistol grip/stock) on my mossberg 500, i dont have to register it or pay a tax do i?

diesel

Not as long as the barrel is over 18".

As long as it is still over the federal minimum length (if I recall correctly, that is 26 inches for a shotgun and 24 inches for a rifle, anyone confirm this?) then no fed tax or registration.

State laws vary, you'll need to research (might want to ask in the Ohio Hometown Forum on Arfcom, seem like a helpful group there). Here in Michigan, if it fell under 30 inches, it would require registration as a pistol (no fees though).

Careful how you hold that thing. A buddy of mine who thought he knew what he was doing held mine at too much of an angle. His wrist hurt for months! (wouldn't listen, sorta served him right ).

I've found it best for me to keep my forearm parallel to the shotgun and allow the elbow and shoulder to move back and forth with the recoil. YMMV.

ETA, the above refers to firing "from the hip".

He said it's a Mossy 500, so with 18" barrel it is over 26". Mossy sells them that way. If I may offer some advise, I've bought many after market pistol grips (Tac-Star, Speed Feed, butler creek....) they're all in a box labeled "parts", the only pistol grip I still use, and it's on my favorate shotty, is the Mossberg factory cruiser grip. It's the only one I find ergonomically correct.