I work at a gun shop in Kokomo and have sold quite a few .500 Handi rifles....I say use the 20ga!! Most guys arent getting the groups they want and it kicks like a mule!! You can get about 150 yards with the Hornady 300grn sst bullets but your 20ga will do the same. You may want to look into Hastings slugs for it. I had one and shot lightfields also and it was a tack driver!! Dont waste your money unless you just want something new!