(The following is typed with a grin.) It's real easy. All you do is send the gun and the money to the correct gunsmith and in a few months to a year you'll get your 20ga double rifle back. Cost= sleeving new rifled barrels into the old monoblock $1500- 2000, cost of two new barrels $200- 300, cost for ammo and regulating $100 to 500.