benjamin co2 pistol .Help please

[titan bearcat]

Hi all, ive got a Benjamin .20 co2 pistol with a problem.Everytime I load a co2 bulb in the gun and screw down the plug , the gun lets all of the pressure from the bulb go before I can even get a single pellet loaded. Ive taken it to bits but cannot see anything wrong with it. I gave up with it about 7 months ago, but I really would like to start using it again. Any ideas ? Thanks

[flatrajectory]

You obviously have a knackered seal or valve, this is not uncommon. As there are several versions of this pistol, with different valve units it is not possible to be more specific on here. You will have to have it looked at by a repair man.
Shame you do not live near me, but most decent gunshops will have a qualified repair person on their books, so try your nearest dealer.
Pete.

[titan bearcat]

Thanks Pete, im not sure if bits are readily available for the pistol. I only put half a tin of pellets before this happened ! Will try my local gunshop.

[pushycheese]

Pete, do you think a drop of pellgun oil would help? Occasionally have same issue with my Walther Cp99.

Dan

[flatrajectory]

Pete, do you think a drop of pellgun oil would help? Occasionally have same issue with my Walther Cp99.

Dan

Your cp99 is a different beast to the Benjamin. If you have the problem intermittently then a drop of pellgun oil will help. But usually if the gas escapes rapidly when the bulb is pierced then you have a major seal failure.

To anyone with a co2 gun that leaks slowly after piercing, just keep cocking and firing,cocking and firing and the leak will usually stop. Slow leaks can be caused by dry seals or by metal debris from the pierced bulb depositing themselves on the valve seat. Repeat firing ( without pellets) ,will usually dislodge the offending particle.
Pete.

[TonyL]

Pete,

I've never owned or worked on one of these little beauties. Will the valve design be similar to the Crosman 2240 type? If so, very few components involved and very easy to work on, at a guess??

[flatrajectory]

Pete,

I've never owned or worked on one of these little beauties. Will the valve design be similar to the Crosman 2240 type? If so, very few components involved and very easy to work on, at a guess??

Yes Tony, the valve design in the Crosman is very similar to the Benjamin, in some versions they are pretty much identical.
Both Benjamin and Crosman have over the last 30 years or so made slight changes to the valve units ,but they are both very simple to work on.
Obviously, you must not dismantle a co2 gun unless the co2 bulb is empty removed.
I imagine there will be strip down guides on youtube for these pistols, but if you get stuck I can run you through it.

Pete.

[Benelli B76]

I make the polyurethane seals for these on my lathe (only for local friends). The old type Benjamin needs a special stripping tool for the valve unit. One thing to try before checking the seals is to cock the pistol before installing the CO2 cartridge. The spring holding the valve seal against the brass sealing ridge may be weak and the hammer spring may be holding it open. Only had one really difficult one to work on belonging to gingernut on here, was blowing gas down through the grips, had to turn up new complete valve made from his brass poker set on the fireplace !

Baz

[flatrajectory]

I make the polyurethane seals for these on my lathe (only for local friends). The old type Benjamin needs a special stripping tool for the valve unit. One thing to try before checking the seals is to cock the pistol before installing the CO2 cartridge. The spring holding the valve seal against the brass sealing ridge may be weak and the hammer spring may be holding it open. Only had one really difficult one to work on belonging to gingernut on here, was blowing gas down through the grips, had to turn up new complete valve made from his brass poker set on the fireplace !

Baz

So now he has to poke the fire with the Benjamin pistol....!!!!! lol.

Pete.

[gingernut]

No,just a shorter poker.
Baz only cut off the end to make into a valve.

[ikarma70]

My eb17 had a bad seal when I got it so I just stripped it and replaced all the seals just to prevent future leaks, it's an easy gun to strip.

[Benelli B76]

The one most likely to give a headache when trying to replace is flat polyurethane exhaust valve seal which is fitted into the cup on the exhaust valve.
Most people ignore these when doing a seal replacement. I have to make these on a lathe a la Lawrie's proven method.

Baz

[titan bearcat]

I stripped mine down again yesterday and examined the seals that I could see, nothing amiss there. Im not sure how to get the brass bit with the needle valve apart, so I left this alone. Popped it all back together and put my last co2 bulb in, and screwd the cap down.....and ....it let the whole c02 go in 5 seconds flat Ive given up with it now, Anyone care to fix it for me if I send it and pay for your time ?

[Doxbox]

I stripped mine down again yesterday and examined the seals that I could see, nothing amiss there. Im not sure how to get the brass bit with the needle valve apart, so I left this alone. Popped it all back together and put my last co2 bulb in, and screwd the cap down.....and ....it let the whole c02 go in 5 seconds flat Ive given up with it now, Anyone care to fix it for me if I send it and pay for your time ?

PM me.

[scgevans]

I might be being stupid......but I thought you had to cock it before putting new gas in ...certainly one of my current or ex pistols or rifles needed this....might be wrong though and clearly dont put a pellett in it!