Then it's an old
Mares Sten Medi (70cm)
In order to depressurize the gun and reinflate it at a known pressure based on the pump strokes / pressure table you will have to push a pin in the hole in the middle of the valve at the back of the gun (needless to say you will unscrew the plastic cap at the rear of the handle). Before you do that, it is advisable to let the gun rest for approx. 15min in a muzzle up position (e.g. leaning against a wall). This will limit the amount of oil / oil vapour that will be released.
The Cressi pump won't fit on a Mares gun (different thread).
Cheers, ulysses
