Sizing seals in springers

[NickG]

I seem to have learned a lot about TX cylinders from this thread, as well as about sizing seals. I certainly was fooled by the cross hatching into assuming it had ben properly honed, but I noticed the tube has clearly been rubbing oppsite the shoe recess. I have no internal mike to check with, but the gun was running with only a few fps variation with the old piston and seal, so any variation in diameter shouldn't be a problem. It is now back together with a tight (but not ridiculously tight, as it was out of the box) seal, but only giving me 9.5 with 42mm preload, I suspect due to the tight seal. I'll put some pellets through it in the garden tomorrow, then see if that improves things.
I don't think I am brave enough to try Tony's idea of boiling the whole assembly - has anyone tried it?

A chap on the other forum has boiled a few hw ones and reports great success.
Michael did you use the piston you had off me , It was standard so you should have been able to just drop the seal on that you were using in that comp tube originally, if its only doing 9 The seal would need to be pretty tight I would be looking at making sure your end cap is sealing.
A word on o rings and cylinder quality, way back when I first started using o rings in the tx I found that they would only make power with a relatively thick cross section, and what I now know to be a high amount of crush (.010" on diameter). The reason for this is to take up the ovality in the tube , The tube I use for reduced cylinders is much better quality wise and allows me to use smaller section rings with a fraction of the crush , so a smaller contact area less friction and the same power for less spring,
The synthetic piston rings are another story all together and surprisingly efficient .

[Shed tuner]

A word on o rings and cylinder quality, way back when I first started using o rings in the tx I found that they would only make power with a relatively thick cross section, and what I now know to be a high amount of crush (.010" on diameter). The reason for this is to take up the ovality in the tube , The tube I use for reduced cylinders is much better quality wise and allows me to use smaller section rings with a fraction of the crush , so a smaller contact area less friction and the same power for less spring.

yup, there's far more choice of seal when sleaving down with half decent quality seamless tube, whether on the TX, HW, PE, anything. I guess with parachute type seals, the manufacturers just didn't bother upping the tolerance, but even with these para seals, you do sometimes get comp tubes that just aren't very efficient, due to air leaking as the seal can only adapt so much / so fast. I did hone (badly) a crap one once and it did gain an extra 0.75 FP afterwards, so a definite improvement (seal sizing was discount after numerous swaps).

The synthetic piston rings are another story all together and surprisingly efficient .

You little tease, you. TonyL will be getting ever so excited (but they do look good)

[TonyL]

You little tease, you. TonyL will be getting ever so excited (but they do look good)

You know me so well, JB.

I'll be very interested to get to know more about these rings, though.

BOING!

[Vernal]

[QUOTE=NickG;7940487]A chap on the other forum has boiled a few hw ones and reports great success.
Michael did you use the piston you had off me , It was standard so you should have been able to just drop the seal on that you were using in that comp tube originally, if its only doing 9 The seal would need to be pretty tight I would be looking at making sure your end cap is sealing.

Yes Nick, it is your piston, but I couldn't use the old seal as my piston has a Tinbum nose extension, which uses a Weihrach seal and I didn't have a spare AA. I was getting 11.3 with the old set up, so assume the cylinder is OK. The new seal, from Chambers, was very tight on fitting and still is quite tight after some resizing.
I put 30 shots through it this afternoon, which made no difference at all, so I upped the preload to 45mm which gave me a smidgeon under 10. Tomorrow I shall put lots of shots through it and if that doesn't get me to at least 10.5 I shall have another go at resizing using one of the many helpful methods suggested here - purely because it must be quite inefficient to be under 10 as set up now. On the other hand, it does feel very nice now, and I am getting the most consistent one holers at thirty yards that I have ever had from the TX. Perhaps I shall learn to love it after all.

[Shed tuner]

if you are building this for benchrest, and you are shooting one holers, I'd leave it alone

[NickG]

Michael I have a selection of used tx seals Shall U send you one, I can select one and try it in a brand new tube I have here .

[Vernal]

Michael I have a selection of used tx seals Shall U send you one, I can select one and try it in a brand new tube I have here .

That would be really kind thank you Nick, and would let me find out if the seal really is the problem before I go on to mutilate anything else.

[Vernal]

Nearly half a tinful through oday, and still 9.9 _ time for a seal change

[NickG]

That would be really kind thank you Nick, and would let me find out if the seal really is the problem before I go on to mutilate anything else.

Ok will look one out tomorrow

[Shed tuner]

have you checked your breech seals ? Not sure how old the gun is, but that can compress and go hard over time...

[Vernal]

if you are building this for benchrest, and you are shooting one holers, I'd leave it alone

The story of my life I suppose - never know when to stop!

[hmangphilly]

The story of my life I suppose - never know when to stop!

stop when you start going backwards