[Alex Johnson]

I remember reading an article in the NRA gunsmithing manual where they were accurizing a ruger. Barrel was removed off this one by cutting the old barrel off and boring out the stub until the threads could be collapsed. Seems extreme but I guess that would be one way of doing it if you had no use for the original barrel in the first place. Of course at the time this article was written there wasn't near as many options for the MK series in the ruger line. I shot competition for years with a MK II and the accuracy from a standard factory barrel far surpassed my talents as a marksman, seems to me a replacement trigger, target grips, and perhaps different sights are all that should need to be done to a stock MK II to make it a viable competition gun and none of these things as Jim says requires the barrel to be removed.