As far as I know, all the RPs were made with 4" barrels and square butt frames. This gun appears to have a 2.5" barrel (or thereabouts) and is not original. The frame also appears modified into round butt configuration. Or, there is the outside possibility that the frame is a Terrier and original in round butt and a cut down RP barrel was installed for some reason. A close examination of the frame should reveal whether it looks original or reworked.

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