Shotguns .410 through 12 gauge (with the exception of the 12 gauge ultra slug) are all the SB1 shotgun frame. The 10 gauge and 12 gauge ultra slug are the special "sb2" reciever. Not the rifle "sb2" reciever, but a shotgun 10 gauge "sb2" reciever. Why it's not labelled an SB3 I'll never know...
Anyway, the huntsman barrel will go on any SB1 shotgun frame, so any .410 to 12 (except 12 ultra slug) shotgun.
H&R makes a 50cal huntsman/ 12 gauge combo, if that interests you. Unfortunately they don't make a 50cal/20 gauge combo.
later,
scruffy
