I enjoy shooting 22's and like the ability to convert existing auto pistols to fire 22's. I recently acquired a Colt series 80 22 conversion unit for one of my Colt 1911's, to go along with conversion units I have for my Italian Beretta 92FS and my German Sig Sauer P 220.
Here's an early Post War .22 Conversion Unit mounted on a '64 vintage G.M. frame. I recently purchased the boxed late 70's .22 Conversion Unit and this is the sellers pic. The #2 slide stop is not shown in the pic and the recoil spring plug is an extra that is not included in this vintage of Conversion Unit. If member 4barrel see's this, I would like to thank him again for allowing me to purchase an absolutely mint period correct magazine for my Post War Conversion Unit. Thanks very much Gary!
I have a .22 Conversion kit in a wooden Pachmayr box, for the model 39 / 59 and works on the the 5906, too. IIRC it's made in Germany. I've had it for 25 year and used it just once but I've never seen another one.