Hammerli repair/maintenance question

[JHinman]

I have a Hammerli AR20 PCP. When new I could leave the cylinder in the rifle when I was not using it. As time went on, it began to bleed off over night. Now it will empty the cylinder in a few hours of non-use.

The cylinder will hold air if it is not in the rifle.

What causes the air to bleed off? How do I fix it - hopefully there is a seal that is easy to replace!

Thanks for any advice!

[rockdrill]

From your description the problem is not the cylinder valve itself.

Although I don't own an AR20, the problem is likely to be one of three thing that come to mind.

1. There is probably an o-ring seal that seals the joint between the regulator and cylinder when it is screwed onto the rifle - check and replace as you could get a slow leak from that point.

2. Regulator seals - possible failure of one of the seal in the regulator assembly allowing air to leak.

3. Problem with the firing valve itself allowing leakage.

Unfortunately as I haven't owned one of these I cannot advise about fixing it but the above are the areas worth investigating.

[56S]

The slower the leak the harder they are to find. My Benjamin Maximus started losing around 200 psi over a week and I just depressurized to and tore it down. The leak was very obvious at that point with corrosion present on the gauge block. Since your leak is larger than mine it should be easy to find. To check the valve seal I closed the bolt and put a balloon over the muzzle. Fill ports and gauges show leaks as bubbles with diluted dish soap.
I expect the PCP guns will eventually all leak if using a hand pump without a good moisture trap. Oh well, three years before a cheap and easy reseal is acceptable for me.