Benjamin Marauder .22 transfer port 1/4 tubing

[anonymous_.457]

I get the best velocity gains when porting and polishing the transfer ports by simply blending and radiusing the sharp drilled corners of the ports. High pressure air needs a smooth flow to increase velocity, so the air isn't going around a sharp 90° corner. I use a Dremel tool with small carbide ball shaped cutting bits to knock off the corner edges, to essentially create a curved pipe for the air to flow through.View attachment 488633View attachment 488634View attachment 488635

I just ran some 15 grain pellets over the chrony it will do over 1000 fps for about 40 fpe that's with the valve drilled to 0.203 and barrel port at .166 and the breech hole opened up a lot I got a piece of tubing in the breech port hole and my trasnfer port stuck into that to get it to seal