I have not done a spur call with the skin, but I have done a few without the skin. There's a ridge on the leg bone that needs to be filed down for it to fit inside the bell end (humerus). If I was going to do one with the skin on, I'd strip off about 1/8 to 1/4 inch of the skin on one end, like stripping a wire, and file down that ridge on the bone just enough to slide it into the bell end. Use quick set epoxy to glue the pieces together, I use JB Kwik.
Also that epoxy coat on the call is some fancy rod building epoxy for fishing rods. The call has to be turned on a rotisserie overnight at minimum for it to set up, or it will run and drip off one side of the call.
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