Pump mag "double cocking"

[zulubravo44]

For lack of a better term, I'm getting frequent "double cocks" with my pump mag. What I mean by this is that a single pump primes the 'mag for its first normal shot, but then something about how I have it set up leads to a second priming and a second shot. I've tried shooting it straight up, upside down and all manner of different ways, and it has never resulted in a triple shot. But it pretty consistently leads to a double shot.

The bolt spring I'm using is the oldest one I have, and I've already cut about 1 1/4 rotations off of it. Any other ideas than cutting the bolt spring?

It's a lvl7 bolt on an AM valve, btw. I've only tested it with compressed air.

[captian pinky]

have any pics of how the bolt is setup? bolt spring length on the bolt, wave spring with bumper etc

[river031403]

Have you chronographed yet is your pressure too low or too high

[Laku]

I would guess the reason is either bolt spring or wave spring.

[athomas]

Do you mean it is shooting twice per trigger pull? Or, do you mean that you can pull the trigger twice and shoot twice?

If it is shooting twice on two trigger pulls (operating in semi), then the bolt is resetting far enough to catch and also to open the on-off and allow the front chamber to charge. The wave spring should prevent this, especially with the shorter worn bolt spring causing the needed bolt stick. If this is the case, you need to find out what isn't preventing the bolt from resetting. I suspect this is not the case and the problem is actually the next version.

If it is shooting twice per trigger pull, then the on-off is most likely opening prematurely or leaking which is charging the front chamber and causing the bolt to fire again as it attempts to reset. Ideally, the wave spring prevents the bolt from resetting and doesn't allow the sear to rotate forward to open the on-off. If the on-off can open without the sear rotating forward, then the on-off is probably leaking, or your pin is too short. The leak is the most likely scenario and can probably be solved with an oring change.