Cocker pump blows bolt back

[Brandon]

I built a pump based on a system x body (not that, that matters). Internals are all shocktech, ccm pump kit (no return spring) Stock WGP Bolt w/orings, ACP Trigger frame with auto trigger and a CP Reg.

I got it all put together, adjusted the reg to around 280-300 and took it outside to try it out. I pull the trigger and it fires a shot but the entire bolt, back block and pump handle travel rearward about an inch. shooting over a radarchron the velocity was all over the board.

I'm thinking it could be because I do not have a pump handle return spring, but I could be 10000% wrong.

Any suggestions?

I do have shocktech bolt and pin coming once angry paintball gets done cutting it for Orings.

[BLachance75]

Are you holding the pump handle?

[XEMON]

I pull the trigger and it fires a shot but the entire bolt, back block and pump handle travel rearward about an inch. shooting over a radarchron the velocity was all over the board.

I'm thinking it could be because I do not have a pump handle return spring,

Put a pump spring in or hold the pump forward 👍

[Alexndl]

You will need a pump handle spring or hold the pump foward when you shoot.
But even with the spring you will experience a small amount of blow back caused by the pressure in the barrel pushing the bolt back.
On sheridan the bolt is held in place by the ball bearing and the holes on the side of the barrel.

[SignOfZeta]

This reminds me of that Lone Wolf video where he’s shooting an Azodin and every time he cocks it he lets go of the pump and holds the reg. Every single shot. It’s exhausting to watch, honestly. Hands moving all over the gun all the time when it already has two handles…as experienced as that guy is, he clearly started with a semi-auto.

Anyway, yeah. Noob troubles will work themselves out when the gun gets used. There’s rarely any reason to let go of the pump during actual play so this isn’t actually a problem.

[jokers]

But if he did not swap hand so often how would he justify you buying his hitman mod and other parts to make your marker better?! You have to think of his bottom line.

[The Inflicted]

I had a Superbolt pump (with return spring) that would somehow gain 10-15fps consistently if I didn't hold the pump back. I never did figure out why.

[Toestr]

Maybe the transfer hole for the valve was drilled too far back? Holding the pump forward would restrict the flow from the valve vs letting it blow back would allow it to better align.

[Jonnydread]

I had a Superbolt pump (with return spring) that would somehow gain 10-15fps consistently if I didn't hold the pump back. I never did figure out why.

I've had pumps that do this too. I generally let go of the pump handle when I shoot because it gives a slightly softer shot with a more predictable trajectory. I don't really move my hand away from the pump, I just "open" my hand for a split second.