Pneumatic Guns

A few months back I acquired a bunch of used gear which included about 6 different spearguns most of which are pneumatic. I did not really have a good grasp on how to use the pneumatic guns so I went into my LDS for information. They told me to stick the pump in the back of the gun and pump away until the pressure became too strong to pump anymore. Well, I followed that advice and everything was going fine, but then all of a sudden the rear valve just opened up and released all of the recently pressurized air. Any further pumps immediately leaked out the back. Does anybody know what's going on here, or have some tips on how to use these things?

Sounds like you blew an O-ring. You will need to replace the ring or seal if that's the case.

Joe

Sideband:

Sounds like you blew an O-ring. You will need to replace the ring or seal if that's the case.

Joe

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Do you think the O-ring was old or faulty or did I pump too much? In other words are you really supposed to pump until the gun won't take any more air?

You should not pump it up until you can't pump anymore as that will overstress things. Well...you already figured that out.

If you had a manual for the gun it would include a chart giving the range, power, or cocking effort required for various pressures/numbers of pumps. Within those guidelines what many divers do is pump the gun up until they can still just barely cock it. Unless you are the governor of California or have very good technique, that limit will be reached before you reach the max number of recommended pumps.

The statement "stick the pump in the back of the gun and pump away until the pressure became too strong to pump anymore" would be more or less correct if you changed it to "stick the pump in the back of the gun and pump away until the pressure became too strong to cock the gun anymore." So the miscommunication that occurred at some point is understandable.

I agree you most likely blew an o-ring, so it will need to be replaced and the gun will need to be servcied. Most pneumatics require a specified amount of oil so that will also need to be replaced when you have it serviced.

DA Aquamaster:

The statement "stick the pump in the back of the gun and pump away until the pressure became too strong to pump anymore" would be more or less correct if you changed it to "stick the pump in the back of the gun and pump away until the pressure became too strong to cock the gun anymore." So the miscommunication that occurred at some point is understandable.

I agree you most likely blew an o-ring, so it will need to be replaced and the gun will need to be servcied. Most pneumatics require a specified amount of oil so that will also need to be replaced when you have it serviced.

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This is exactly where the water gets murky for me because I pumped like crazy over the course of about 5 minutes periodically stopping to load the gun and check how high the cocking pressure was, but it never seemed to get anywhere near hard to cock or seem to make much of a difference.

Sounds like the gun, and possibly the pump, had some issues before you ever started pumping.