Advantage Arms has the hands down best conversion for Glock handguns. I have about 10,000 rounds through one with no problems. Not knocking Ceiner at all as I use theirs in a 1911. Advantage Arms kit is about $250-$275.
"People live too long, dogs don't live long enough" - FTF Member-
I bought an Advantage Arms conversion kit for my Glock 27. It replaces the complete slide with a new 22 slide. You simply take off the complete stock slide and install the new slide. This kit mimics the Glock in form & function. It is a good way to spend time at the range with my Glock cheaply.