Been developing 21mm reduced tube TX

[NickG]

I decided to see if I could improve upon my 21mm TX tune , I know that Jon Budds short port is worth some power so took it to the extreme and made a comp tube end plug to take a 21mm sleeve and provide a 4mm long port using a single breech seal , this increased the spring room considerably, and knowing that a longer spring can be softer and less stressed I also installed a spring guide fixed into the trigger block.This worked well with my original ally piston , the short port allows a much lighter piston to be used without it bouncing, so again went to extreme on spring room and made a very short skirtless piston hoping the rear guide would support the rear , it didn't , the fit of the trigger block in the action is pants so the guide pitched upwards when the screw was tightened , causing friction on the piston.
So came up with a design of full piston( using an x ring to seal) that along with the short port and fixed guide give me an extra 18 mm of spring room .
The gun shoots nicely with very little recoil and is a little softer to shoot, I will attempt to put pictures up to illustrate , and bring it to the bash

https://goo.gl/photos/TQKtWy5jVeq6Vxo28 last picture shows longer spring now used over original

https://goo.gl/photos/1tXjJDGg1Fuv9VdW8 failed skirtless piston

https://goo.gl/photos/Jo5yDFt9nLWZCTQ99 components showing piston design

https://goo.gl/photos/4nQyFpp7ey1hSLQm8 power plant


https://goo.gl/photos/XtUGEfJeLKTCLXZL7 trial short piston to see if the design works