Originally Posted by murphydog

I handled one recently. It is the centerfire ancestor to the 400/600/2200 rimfire pistols of the late 20th century.

Two quirky features; the little wedge in the slide serrations is a recoil spring disconnector, so the action has no resistance when manually cycled. And the (barely visible) semicircular metal piece in the upper rear grip strap is a manual safety!