There are several 22 conversions for the 1911 pistols. Most work well, when you find the ammo they like. I've been using one from Wilson Combat for many years, and if you keep it clean and oiled, it works fine.
I went with the advantage arms conversion. I like the fact that it locks open after last shot (kimber does not) I have used it on a sti spartan 9mm, springfield loaded 45acp, and a taurus pt1911 38 super with no problems. mine likes mini mags, cci blazers and winchester m22 it hates all federals that I have tried Randy
There are two distinct type 22 LR conversion units for 1911's: The type where the whole of the slide moves in recoil carrying the sights with it ; and the type where the sights and barrel are fixed to the the frame of the gun and only a small bolt moves in recoil. The former is used for tactical practice. The latter is more accurate and is typically used for bullseye competition.
One manufacturer that has a good reputation is the Marvel Precision Unit #1 which is the accuracy version and the Unit #2 which is the tactical practice version.
When considering a conversion unit you have to be sure the manufactures unit will fit your gun. It turns out that 1911's typically use different ejectors for different calibers and different manufactures may use different ejectors as well. It seems that some conversion units will not fit some 1911's because of the variation in ejectors. You must check with the manufacturer to be sure but the Marvel unit are not sensitive to the various ejectors Colt uses for the different calibers. Kimber and Ceiners units are ejector sensitive the last time I checked but that was years ago.