Originally Posted by hmangphilly
I attached a snap on cylinder leakage tester EEPV309A00 to the muzzle,
air cylinder fitted but only filled to 30 bar
hammer cocked then released against dry fire switch
join tester to air line
adjust the leak tester to 100psi
I agree with Scooby that this is not the right test to quantify the leak past the valve stem and more important that the leak, if any, past the valve stem is something constant and not effecting accuracy. Steyr, Anschutz, Airarms, FX all use an unsealed valve stem so why would you need a sealed one?
From what I can make of it your test does not measure leak past the valve stem. Because when the hammer is against the dry fire switch the valve is not open. That's the purpose of the dry fire switch: Not opening the valve while releasing the hammer.
With a closed valve the air should not be coming out of the muzzle. You would have noticed if it did because your cylinder fill would be empty after some time of storage.
I don't know where your leaking air at the muzzle is coming from but it is unlikely that it is the valve stem.
The cut away pictures of LG300 breech blocks halfway down on this page http://airgunaccuracy.wordpress.com/...-field-target/
might give a clue.
Would appreciate if you could elaborate on your test.