I can add this one, which I acquired a few weeks ago. I am absolutely in love with this gun, which is accurate and unusual in equal measure. I posted this one recently in its own thread, but this topical thread gives me the opportunity to bring it out again.
This is the rarely seen Model 56, a gun never sold commercially. About 15,000 were made for the USAF in early 1963 (maybe starting in 1962 -- I'm not sure). Most were destroyed at the end of their service life. Only a few dozen are known to have survived. This model's existence triggered interest in a commercially available K-frame snubnose revolver with adjustable sights, so the two-inch M15-2 was introduced in 1964. The M56 is has some features that differ slightly from the later M15 configuration -- smooth backstrap, ungrooved rear sight foot, horizontally grooved ramp front sight, narrow hammer.
Those are the wrong stocks. This model left the factory wearing PC magnas. I'll pick up the right wood for it one of these days, but I expect I will leave the grip adapter on for range trips.