Walther cylinders

[Ade C]

I have a Hammerli AP20 which uses Walther cylinders. I fill with a stirrup pump which is easy enough. What I don't like is having to unscrew the cylinder while under pressure. Apparently these fill adapters allow the pump to be bled before unscrewing but I don't see how

The one supplied with the pistol has an offset hole. Is there any way around this problem?
Compared to other systems which use quick fill probes it seems very low tech

[Gwhite]

There is a pin in the cylinder that opens the valve when pushed. If you have a fill adapter with an offset hole, it pushes the valve open. If you put the adapter hole in the middle, it doesn't push on the pin. It still fills the cylinder as long as the external pressure is higher than the cylinder pressure, plus a small extra amount to push the valve open. Some pistols (Morini for one) rely on this approach from the factory. Others require a modified adapter.

[David Levene]

As you are in the UK, have a look at https://www.bestfittings.co.uk/shop/fil ... -adaptors/

[m1963]

The ones from BEST fittings do allow the tanks to be unscrewed without the loss of any pressure. We have several shooters using them.

[Ade C]

Thanks for the confirmation. Looks like Best Fittings will be getting another £20 off me after already spending money on adapters to allow me to connect to my pump.
Why Walther didn't design it like that in the first place defies logic. Perhaps it's because they can make money on replacement cylinders when the threads have stripped...

[Ade C]

Quick update. Just received the new type fitting which screws onto the quick fill adapter. I can now fill and bleed as normal without unscrewing under pressure. Anyone with a Walther seriously needs one of these!