This bolt design is a neat work around to the classic problem of the rimfire PGP breech receiving air from directly under the ball.
Known as the Rimfire to Centerfire conversion bolt, this design uses a sled to allow the bolt to move further forward in the breech. With the bolt pumped forward, the air is routed from the air inlet hole on the bottom through the center of the bolt and out the face, making it a centerfire bolt similar to what would be used on a PMI 1.
I have heard these were sold by General Joe as the “General Joe’s Centerfire PGP bolt” but I don’t know if Joe made them. Anyone know any history on them?