They should be legal on a pump shotgun under NYS law. The assault weapons ban section that applies to shotguns is for semi-autos only.
(b) a semiautomatic shotgun that has at least two of the following
characteristics:
(i) a folding or telescoping stock;
(ii) a pistol grip that protrudes conspicuously beneath the action of
the weapon;
(iii) a fixed magazine capacity in excess of five rounds;
(iv) an ability to accept a detachable magazine;
Always check your local laws too.