Ok, another new guy here...But I have considered this before joining as well, but in another fashion. I am the proud owner of a PERFECLY fitted side by side 12 ga. with 3" chambers, 26" barrels, double triggers, screw in choke tubes, no bull flat matte finish stock... I was digging for a way to make it a "hog gun", and here is what I found:

CHAMBER ADAPTERS

They make inserts in 2.75", 10", and 18". The longer inserts are RIFLED! Not sure on ballistics, but I would look tothe performance of the Contender barrels-they seem to be similar in length and such. I am going to invest in a single 10" .45-70 as soon as the money comes thru...Maybe put a recessed flip up rear sight too-would make a decent 30 yard hog gun, I think.