Air Arms Owners Club

I stripped and replaced all 0-rings on my s410 because it had a slow leak.i replaced the o ring on the pressure gauge for a dowty seal tightened it up and filled rifle.all was well until the next day I noticed it had lost air,I put a balloon over the pressure gauge and it inflated it.it the problem the dowty seal and should I replace it with a o-ring?

or the pressure gauge is nacked

Dowty seals are designed for flat faces without a groove. The dogleg will have a groove for an o-ring to expand into but the dowty lip may actually drop in and not be compressed. I would go back to the correct size o-ring

TenMetrePeter wrote:Dowty seals are designed for flat faces without a groove. The dogleg will have a groove for an o-ring to expand into but the dowty lip may actually drop in and not be compressed. I would go back to the correct size o-ring

I believe that the dowty seal was at some point used on the s*series but not sure if it was the older or newer models

If it was designed for an O ring, fit an O ring. Apply a tiny coating of O ring grease first, this helps it to seat correctly.

Also depends on where the balloon was fitted. If only on the gauge body then it may well be the gauge bourdon tube knacked as already suggested by ronnie

If the dogleg looks like this with a groove milled into the face where the gauge threads then it deffo needs an O ring.
If it is completely flat with just the thread then a Dowty washer is indicated.

Removed the dowty washer and replaced with an o-ring,filled to 100 bar and left it overnight and all is good.happy days