What is a Sphericon?
The sphericon is a three-dimensional solid with one side and two edges. It was first introduced by the Israeli game and toy inventor David Haran Hirsch who patented it in Israel in 1980. It was given its name by Colin Roberts, of Hertfordshire, England, who also explored it. It may be constructed from a bicone with an apex of 90 degrees, by splitting the bicone along a plane through both apexes, rotating one of the two halves by 90 degrees, and reattaching the two halves. Alternatively, the surface of a sphericon can be formed by cutting and gluing a paper template in the form of four circular sectors joined edge-to-edge. Like the Oloid and other developable rollers, when rolled on a flat surface, every point on the surface of a sphericon comes in contact with the surface it is rolling on.
My Sphericon details
Sphericons can have many different shapes, the simplest and most common ones just would not fill the barrel of a shotgun to my liking. So I developed the one you see in the video. For manufacturing reasons I had to in large the Sphericon and clip off the sharp edges. This lets me use a ball nose endmill to cut the mold and maintain the .729 shotgun bore diameter. What we end up with is a very slightly modified Sphericon slug that is a perfect fit for a shotgun barrel. And one that can be easily cast out of lead with your traditional bullet casting equipment with a custom mold. The slug weighs in at 455gr and as loaded in the video it was traveling around 1450-1500 FPS.
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