my guess is that there isn't enough pressure to kick the bolt back far enough to engage the sear, so it just springs back into the power tube and farts some more gas through the marker. Mine usually bounces three or four times before stopping with the bolt closed.

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Tippmann 98 Custom Platinum Series (non-A.C.T.)
{polished internals, remote, red-dot, TACAMO Arc Loader, RAP4 CAR stock, double trigger, Flatline}

I hope someone will read this :

I've refilled my tank (Finally) and when I screwed it in the gun I heard my valve close (short air burst) then the marker seems fine accept in semi-auto mode it sometimes fires twice... (this time still got 3.000 PSI in the tank) When it does both balls don't get as far as when I would fire a single ball.

Anyone having the same problem ?

Mods that might be the cause:

Zero-Kick hammer (Just installed but the problem started little before the swap)
Cyclone feed system
Electric trigger system

I'll post a film of the strange behavior if necessarily.

EDIT : Link to movie one : Here
Lissen closely and you can hear it "skip"

EDIT2 : Linkt to movie two : Here
Definitively can hear the problem here (Firing around 24 sec. And sorry for the poor lightning)

I read a couple of places that you need to install a stiffer spring when you use the zero kick hammer..that may be the reason for the skip. I would swap back the original hammer and see if that helps any...

Hi there Jrok, thanks for your quick reply.

When I ordered the Zero-Kick hammer it arrived with an stiffer spring and installed it.

Will try to switch back to normal bold tonight to see if it's the problem, also will try to think of a way to measure the kickback with both bolds to see the difference.

Didn't work

With the stock bolt it still skips a lot, maybe even more.

hmmm...have you swapped all easily accessible orings and checked the powertube for cracks??

perhaps the sear-spring is damaged/fallen out or the sear it self is worn? Or have you only tried it with the E-grip installed?

try to put it back to mech and see if the same thing happens. Then you will know if it is a problem with the electronics (settings) or something mechanical at least.