I have been playing with the Ruger .22 target pistols for quite a while. OK, me and Volquertsen.... I decided to go with all Mark III's because I like the thumb mag release and just to have a simple common magazine for all three of my pistols. Last week I picked up a virtually new, Mark II target. As I was replacing the sear on Mark II with a VQ sear I was also upgrading a Mark III Hunter with the same part. I have been wondering for some time if Mark III magazine might fit in a Mark II. This is important because its really hard to find any Ruger Mark anything mags and I finally found a source on line for MK III's at just under $24 each shipped. Because the MK II has a small bump on both sides of the mag I assumed they would not fit in the frame. Wrong! It fit fine in the MK II. I had both frames side by side (without the barrels) and MK III mags in each and they line up fine and seat fine in the MK II. Huh. Shoudda done this sooner.... In an on-line search, I find guys that say, nope, won't feed right and others that say they work fine in a MK II. Anyone with any experience on this? Weather permitting, I will get to try this on Friday and see what happens. Worst case the bumps could be ground off for exclusive MK II use but since I have both frames I want to keep the interchange going. Once you remove the magazine safety parts on the MK III, they shoot exactly the same.