I have trying to get a 4" bull barrel 22/45 (like the one in the classifieds now), but I settled for a 5.5" bull barrel instead. I already had a bid on it when the one came up for sale here. I'm going to put the barrel from my 50th aanniversary model on the 22/45 for a light weight gun for my wife, and put the bull barrel on the 50th since I have a complete Volquartsen group in it. I prefer the standard grip frame over the 22/45 grip. There have been lots of MKIII's for sale, but the MKII's have been getting harder to find.