I put a Ciener .22 Conversion Unit on my 1911A1, which has an ambidextrous safety installed. I use it to practice strong-hand/weak-hand drills for IDPA competition. It's proven to be very accurate and reliable, with the added benefit that it changes back to a .45 ACP in about 30 seconds, so it's 2 guns in 1.
Ciener also makes .22 conversion units for the Beretta 92/96 and the Taurus 92/99.
I put an Advantage Arms .22 Conversion Unit on my Glock 30, and like it even better; it comes with adjustable sights standard, it's easier to swap for the .45 upper unit, and Glocks don't have any safetys to fool with, anyway. They're not as cheap as the Ciener units, but the quality and accuracy is first rate.