Persistant HW 100 leak

[Shedder]

A relative bought a seal kit for an S200 that were supposed to be the right size etc. I think that they were off the Evil Bay. Turned out that one of the seals was completely wrong. I think part of the problems is that some sellers may not be aware of the various different changes to airguns through their production life, such as the different fill valves on s200s of different ages/marks.
The moral of the story, I'm sure, is to buy seals and o-rings from reputable suppliers, even if they aren't the cheapest.

[Blackmax]

A relative bought a seal kit for an S200 that were supposed to be the right size etc. I think that they were off the Evil Bay. Turned out that one of the seals was completely wrong. I think part of the problems is that some sellers may not be aware of the various different changes to airguns through their production life, such as the different fill valves on s200s of different ages/marks.
The moral of the story, I'm sure, is to buy seals and o-rings from reputable suppliers, even if they aren't the cheapest.

I've had poor kits off Knibbs for a couple of guns I've been fixing but for £5 you can't beat the HW100 Tuning minor service kit, I've never had a problem with any of their products. The O ring kits cover every eventuality and every variant, I fit them in all the guns I service and that's a fair few now.

[Artfull-Bodger]

There can be a tolerance issue on the inlet valve, you sometimes have to try a BS005 alternative to get it to seal reliably, I recently had one in that would not seal no matter what ring was used, in the end I changed the inlet valve and that cured the problem.

I suppose if your air cylinder inlet bore is close to max tolerance and your inlet valve spigot close to bottom you could get a stubborn leak, after all they are made to production tolerances not absolute precision.

HW100 Tuning is a good supplier however, all the rings I have bought off him have been correct to model and size.

[Benelli B76]

There can be a tolerance issue on the inlet valve, you sometimes have to try a BS005 alternative to get it to seal reliably, I recently had one in that would not seal no matter what ring was used, in the end I changed the inlet valve and that cured the problem.

I suppose if your air cylinder inlet bore is close to max tolerance and your inlet valve spigot close to bottom you could get a stubborn leak, after all they are made to production tolerances not absolute precision.

HW100 Tuning is a good supplier however, all the rings I have bought off him have been correct to model and size.

I service 5 or 6 rifles a week and never had this problem before with the 100 which I find is one of the simplest rifles to work on. What you say makes sense. Fortunately I have a huge collection of O rings in various materials. The polyurethane one that worked was a tight fit on the valve and of a very high Shore hardness, almost like nylon, and sealed well.

Baz

[Artfull-Bodger]

I service 5 or 6 rifles a week and never had this problem before with the 100 which I find is one of the simplest rifles to work on. What you say makes sense. Fortunately I have a huge collection of O rings in various materials. The polyurethane one that worked was a tight fit on the valve and of a very high Shore hardness, almost like nylon, and sealed well.

Baz

Yes it is rare that you just cant get one to seal, I have only seen two and only one had to change the valve, and like you I service these regularly.

What's bizarre is the o-ring works by deflecting under pressure and basically jamming itself into the gap causing a seal, so a softer one should work better as it's not a gasket, but sometimes the poly ones do work where rubber fails, I can only conclude it's a tolerance thing?