oktx;
dont qoute me on this but from what i have read about these guns;
the huntsman is listed as a firearm by the ATF (and is subject to firearm regulations)
the sidekick is listed as a muzzleload only gun (i dont think H&R will mount any other barrels to that frame.)
also the sidekick has a 2 or 4 inch longer barrel than the huntsman and is able to shoot heavier powder charges Up to 150grains max vs. 100grain max. for the huntsman.
I dont own the sidekick...but have a huntsman that i ordered through the H&R barrel accessory program. for a partner shotgun frame.
TCB