If you have a problem with only one pistol cylinder I would say it is a problem with its valve closing. The opposite can also happen when transferring too much liquid CO2 when you get valve block and need to use the venting cap. Any residual gas trapped between the extinguisher and cylinder when the lever is closed is at about 820 p.s.i. so it does make a noise.
Baz (see pic)
https://i.imgur.com/1ADwNgG.jpg
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Hello Benelli76. I suspect is the shout off valve I changed the O ring but not get results inside there is one M3 brass wash I go to add other two to give more pressure on the spring.
when I lived in Italy I have one Benelli custom chambered 7.65 long barrel, and after became the b80 sport.
Thank you for your suggestion.
Katanga.
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Hello the fire extinguisher is the same on the picture and shout immediately, only the Walther filler adaptor is connected, I fill another cylinder and not a problem.
I changed the O ring on the shutter valve and doing the same, I changed the spring and the same, the green O ring luck ok, I put the cylinder on the pistol and is ok.
This cylinder has the problem BANG! this worried me.