At Glockmeister, a 4473 was filled out and my old frame was returned to me, much to my surprise. (I purchased a new complete lower) I didn't know that was the protocol. On the way home, it hit me, I could order the Advantage Arms kit and have a dedicated Glock in .22 rimfire. That was an expensive day, but I am very happy and the wife now has a light on her Glock 17 nightstand gun.
A complete lower is not much more $$ than the bare frame.
While I was there, the Glock meister ultrasonic cleaned my Glock 21, installed new springs in it, and upgraded the ejector assy. Free.
I also bought some other trinkets for my other toys, like extended slide take down thingees and extended slide releases.
I considered sending it to Glock, but the walk in, walk out, spend money, have new gun now was just too much to resist. Glock was about a 6 week turnaround and you have to spend $30 to overnight it to them and probably the same to get it back.