I did one once on a H&R Buffalo Classic. I made a 1/8" thick steel plate, in an oval shape, I then inletted the area behind the receiver to fit the plate and drilled a hole to countersink a wood screw through the plate, and into the stock. I put Acraglass in the stock recess, and set the plate into it with the wood screw secured. Then simply mount any tang sight to holes you can drill and tap into the plate. This makes a very secure mount.