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

[hydroclamp]

Good old photobucket carnt see pics

[NickG]

Thats weird I have tested them and they work for me .

[hydroclamp]

https://flic.kr/p/XpZxvZ

[Shed tuner]

sounds good mate, I like it. Spring room really helps guns shoot nice; I think that's why sleaved HW80s and Pro Elites are so soft...

Photobucket has blocked third party hosting for everyone BTW, so no-one will be able to see the pics - you need to use another provider

[NickG]

ok will try flicker

[TonyL]

So you're coming to The Bash, Nick?

EXCELLENT!!

[NickG]

So you're coming to The Bash, Nick?

EXCELLENT!!

Yes will be there on the saturday, looking forward to seeing everyone again.

[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

I have edited the post hopefully the images will show now , nb the final design has the full ally piston installed

[hmangphilly]

I have edited the post hopefully the images will show now , nb the final design has the full ally piston installed

good work nick .

are you making the end cap from scratch ?

just wondered why you kept with the hex


oh yeah

thought about boring the trigger block , to get a bit MORE spring room ?

hows the spring clearance to the inside of the piston tube ?


and

could you go lots longer on the rear guide ?

get it shooting , and start counting the shots for us

[NickG]

good work nick .

are you making the end cap from scratch ?

just wondered why you kept with the hex


oh yeah

thought about boring the trigger block , to get a bit MORE spring room ?

hows the spring clearance to the inside of the piston tube ?


and

could you go lots longer on the rear guide ?

get it shooting , and start counting the shots for us

Had to do the cap from scratch to get the room, made the hex so i could get it out , it only has loctite on the liner diameter, next one is only having the thread in the liner and just loctite into the tube , no hex one thread ,easier.I have a 19.8 mm ream for the piston bore , so around 1mm clearance it doesn't bind , The x ring gives a little extra power to the o ring as you run them with less crush.
I have the shorter spring version in my target gun and its holding up, hoping this one is the answer so its going in .