I started a double barrel shotgun conversion, I bought a mid 70's Merkel SxS and then bought 2x 43 Mauser barrels off 71/84's turned the barrels to slide in the shotgun tubes with a flange (made the knox of the barrel look like a 12 gauge case) and cut the to 28" then installed them in the tubes, I was going to silver solder them in place but I loved the fit and feel of the shotgun so much, 3 years later its still a 12g and I've been holding onto the 43 Mauser barrels waiting for another SxS

my plan was to used set screws or wedges/eccentric rings I the muzzle to regulate the barrels. I was just planning on setting them both up for 75m with a 360 cast bullet and a case full of hodgdon 777 not compressed