RE: (super-noob question) which brand to start?
You have to have an SB2 Frame to put high power rifle barrels with a muzzleloader barrel the Sidekick is only a muzzleloader frame and no other barrels are available for it. The huntsman will take shotgun barrels. H&R did sell a SB 2 frame with 243 and muzzloader barrel check thgere we site