"The rear of the cylinder has been releaved for a full-moon or half-moon clip system."

Don't think so. Look at the side view. There is no room there for moon clips. This is a cylinder that had recessed chambers, either a .22 Long Rifle or maybe a .22 Jet. I haven't handled a .22 Jet in years and I'm not sure it was recessed.

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John 3:16
WAR EAGLE!