I just picked up one of these switch-barrels in the 12 ga. rifled slug configuration (too good of a deal to pass up - a new gun for the price of a Hastings barrel, and one I can convert to a rifle). However the deal was only on the shotgun, no rifles. Mossberg's available rifle calibers aren't too interesting and I was wondering what'd be the best way to end up with a 45-70 barrel for it.

I considered 2 options: Find someone who makes an aftermarket barrel or buy one of the factory 223 or 22-250 varmint barrels and have it rebored and chambered.

The rebore and rechamber option is probably cost prohibitive, which leaves me looking for an aftermarket component barrel or someone who could chamber and fit a barrel from a blank (I think).

Any suggestions? Thanks. -WSJ