TX200 piston seal lost volume

[cooper_dan]

Just to add more to the current TX thread's....

I've trawled through the search function but haven't been able to find what I'm looking for, which is....Has anyone successfully filled in the lost volume at the front of the TX piston seal, or is the only option to buy something like the Aussie version?
Here's why:

- This week I've swapped out my o-ring breech seals for a 1 piece version made of harder rubber
- The shot cycle now feels a bit more 'slammy'
- My current theory is that the softer o-ring seals absorbed some of the force of the piston when it comes back the second time with no pellet in the barrel. The new harder seal doesn't absorb as much force, so the piston 'slams' a little bit harder which is enough to be noticeable
- Measuring compression ratio gives about 365:1 if you just consider the TP
- This drops to 210:1 if you add in the empty space in the middle of the standard seal

Question 1: am I correct in thinking that increasing the compression ratio up to 350 ish will help cushion the piston on it's second go forward?
Question 2: Has anyone filled in the standard piston to achieve this, and what did you use? Was is a reliable solution?

I've got an aussie seal on order but want to have a play in the mean time. Going to leave the TP and piston standard for now as I know I can go back to how I had it before (with the o-rings)

[pjinoz]

Just to add more to the current TX thread's....

I've trawled through the search function but haven't been able to find what I'm looking for, which is....Has anyone successfully filled in the lost volume at the front of the TX piston seal, or is the only option to buy something like the Aussie version?
Here's why:

- This week I've swapped out my o-ring breech seals for a 1 piece version made of harder rubber
- The shot cycle now feels a bit more 'slammy'
- My current theory is that the softer o-ring seals absorbed some of the force of the piston when it comes back the second time with no pellet in the barrel. The new harder seal doesn't absorb as much force, so the piston 'slams' a little bit harder which is enough to be noticeable
- Measuring compression ratio gives about 365:1 if you just consider the TP
- This drops to 210:1 if you add in the empty space in the middle of the standard seal

Question 1: am I correct in thinking that increasing the compression ratio up to 350 ish will help cushion the piston on it's second go forward?
Question 2: Has anyone filled in the standard piston to achieve this, and what did you use? Was is a reliable solution?

I've got an aussie seal on order but want to have a play in the mean time. Going to leave the TP and piston standard for now as I know I can go back to how I had it before (with the o-rings)

Hi
If you increase the SCR ratio there is a good chance that velocity will increase taking you over the 12 fpe limit. Whilst one might think there may be an extra cushioning effect due to the extra air compression you have to consider that the air will be heated much more and simply "calculating" the increase SCR 210 to 365 may be completely 'out of wack" due to the very much hotter air and thus much higher pressure. Hotter air will flow through the transfer port much faster than colder air. So if need be check your energy level.

Cheers
pjinoz

[cooper_dan]

Hi
If you increase the SCR ratio there is a good chance that velocity will increase taking you over the 12 fpe limit. Whilst one might think there may be an extra cushioning effect due to the extra air compression you have to consider that the air will be heated much more and simply "calculating" the increase SCR 210 to 365 may be completely 'out of wack" due to the very much hotter air and thus much higher pressure. Hotter air will flow through the transfer port much faster than colder air. So if need be check your energy level.

Cheers
pjinoz

My chrono is always on hand when I make any changes. I'm expecting the power will rise slightly, and I've got 4mm of pre-load washers I can remove if needed.
I'm more interested in the feel of the shot cycle though, and if it will 'soften' the piston landing after the pellet has left the barrel

[BTDT]

If you're in no hurry to get away after this Sunday's springerfest, Dan, I could record the shot cycle and see what it is that you're feeling as 'slammy'.

[cooper_dan]

If you're in no hurry to get away after this Sunday's springerfest, Dan, I could record the shot cycle and see what it is that you're feeling as 'slammy'.

I'll be no rush to get away but it's too late, I've already taken the plunge and made a modification.

The best I can describe it is that before, I could shoot the thing all day no problem. After changing the breech seal, the shot cycle felt more 'sudden' through my leading hand. And where my face touches the cheek piece my teeth felt like they were rattling and skin was tingling. It was actually fairly uncomfortable, hence making this change so quickly.

[cooper_dan]

Actually Jim, the modification is reversible. So maybe we could measure it post modification, then strip it down and undo the modification to measure what I thought was 'slammy'. Could be an interesting exercise and I won't be in any rush

[TonyL]

If you're in no hurry to get away after this Sunday's springerfest, Dan, I could record the shot cycle and see what it is that you're feeling as 'slammy'.

As usual from The Gentleman of Springer Deity, what a lovely, generous offer.