Well, i'm here with Wade's book and they sure look like the Silencer mark IV, but the picture shows a ferrule that is pretty parallel up to the last third, Others are not shown well (side views)and some of the other Silencer heads sure enough have tapered ferrules, so I can't say for sure. BTW. In the section for Indian, it states that the Indian is actually made with Silencer parts, and it changed along with the changes in the Silencer (there was a lot of that back then). The Pix for the Indian heads ALL show the bleeder blades as inverted, that is, the main blade is exactly the same, but the bleeders are like a big "V" shape with the wings pointing forward. This is not one of those Indians, at least in that respect.
ChuckC