Just lucked into one of these. The slide was made by Peters Stahl, who made the Springfield Omega. This is the rarest of the 22lr conversions for the 1911, and certainly the most accurate. Uses Colt Ace magazines. Surprisingly, it uses a light 1911 recoil spring in a reverse plug configuration. Shims are used to fit the unit to the gun. I decided I'm going to fit it to my Omega frame, turning the Omega into a dual caliber Peters/Stahl gun.
Gunsamerica. The dealer, in Arizona, said he had no idea what it was, had never seen another one, and that it was "still packed in Cosmoline". It was kind of expensive. There is almost no intel about these online, I'll write it up in detail when it arrives.
Surprisingly, it was indeed still packed in Cosmoline! Good thing, since it was socked away in a box for 30 years. Came with three front sights, but damned if I can budge the Baughmann that was stuck on by the factory, I'd like to put the undercut Patridge on it. The whole thing is blued steel.
Thought I should document the fitting procedure here since nobody else has ever bothered. The locking block, visible in the picture of the bottom of the slide, is held in with 2 allen screws. These screws are removed for assembly/disassembly of the unit. The unit comes with a set of shims that are installed under the locking block by trial and error until the slide stop pin fits just barely loosely enough so that it can turn to lock the slide back on an empty magazine. Buying a two piece slide stop from Nelson Custom would make for a much better solution, since the pin can be installed to a tighter fit without interfering with lockback. Be aware that the slide must clear the hammer at it's full rearward position, and choose your hammer accordingly. Also, I recommend keeping a second mainspring housing handy with a 18lb spring in it for use with this (or any) 22 conversion unit.
