Yes, the two-screw target grips will fit on a stepped ("rebated") frame. You would just end up with a small internal void between steel and wood. Nothing is visible from outside the gun, and the stocks do not slide around because of the lack of frame/wood contact over that inch to inch and a half.

It is true that the rebated frames, as well as the non-rebated frames intended to take the target stocks, usually have the serial numbers on the forestrap. Only the round butt Kit Guns are ordinarily found with the serial number on the bottom of the grip frame. But I have one Kit Gun with a serial number on the bottom and with a rebated frame. But it looks as though the frame may have been filed after shipment in order to take the slightly larger RP stocks.

Kit Guns came with three different stock configurations: round (smallest); Regulation Police (square, larger, and mounted on a rebated frame); and the two-screw extension stocks that completely cover the backstrap (largest). Yes, extension stocks look ungainly on a .22/32 with a four inch barrel.

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David Wilson