I think your project needs a little more definition. Do you need it to handle shot too? The rate of twist required to stabilize a sabot will destroy any hope of a useful shot pattern. If you do not require shotgun performance, then a fully rifled conversion is very possible, but very exspensive. Most guys who do conversions charge at least 3k if not more. Rifled barrels can be obtained through Hastings. I may be able to help, but I need to know what you want the gun to do.
Steve

Firearms imports, consignments


[Linked Image from i.imgur.com]