I just received my Advantage Arms conversion kit for my 21sf. I've taken it to the range twice now & I love this kit. It is a high quality kit that mimics the Glock in form and function. The slide even locks back on an empty mag. It is as accurate as one would expect on a kit of this nature. I am using the Remington golden bullets (both round nose & hollow point) along with CCI mini mags and have had zero ftf's. I expected at least a few at first, so this has exceeded my expectations.
I'm now considering ordering a kit for my Glock 27. I hear that there is a long waiting list for that particular model & can't quite talk myself into having two of these kits for range use. The cost of these kits is $259 so I'm torn because I can buy a Ruger Mark III for that money. Might end up doing that. Heck I don't know what to do.