dumb question about shotguns and such

[Polie]

Is it legal to buy a shotgun with a pistol grip and swap it out with a full stock or a folding stock and vise-versa?

Oh and of course having a 18.5" barrel.

[Raith]

You can do anything you want to a shotgun with a barrel length of greater than 18"

A shotgun with a stock that has a barrel of less than 18" is a Short Barreled Shotgun (SBS) and has a $200 tax stamp.

A shotgun without a stock (And has never had one at any point) with a barrel of less than 18" is a Any Other Weapon (AOW) and has a $5 tax stamp.