Thread your unthreaded Ruger MK 1 Bull Barrels to 1/2-28 RH with this premium grade thread adapter. Made out of quality black oxidized steel, simply slip this adapter over the end of your barrel, tighten the brass set screw, and that's it! Now you can mount standard 1/2-28 RH accessories on the end of your unthreaded barrel!
As not all barrels are the same, please confirm the following specs about your barrel:
Barrel diameter at muzzle: .72 inches
Front Sight Width: .43 inches
Outer Threads: 1/2"-28 RH
Finish: Black Oxide
Set Screw: 1/4"-20 Brass (Allen Type)