Made by mating an old style (aka MkII) 22/45 lower and bolt to an actual MkII 10" (MK10) upper. So far the only "mod" is a Clark hammer bushing and sear pin, although I am sending it to VQ to have the upper tightened to the lower, and having them install a trigger and sear while there. I put 350 rounds through it, and it was perfectly reliable and very accurate. I was surprised at how much quieter it is than my 5.5" 22/45, both shooting the same ammo. Wanna kill these ads? We can help!