x-valves and pumps

[Nobody]

Simple question here. Why do people use the X valve on pump mags? To me the shear idea of it is like putting a Ferrari engine in a minivan, just to go get groceries. You not only are loosing the one advantage of the X valve(the reactiveness/recharge of the valve) but you are also removing the L10 bolt for a L7 and controlled bolt stick.

I only ask cause i am gathering parts for my own pumpmag.

[OPBN]

Weight and anodizability.

[zondo]

Lighten the load. That's about it. And to add a level 10, stock. Obviously with the short pump stroke you run the risk of chopping with a level 7.

[captian pinky]

my xvalved pump mag shoots better than my classic valve ones. lvl 10, rt on/off. i dont know why you wouldnt run an xvalve on a pump.

[lobo_fuerte]

I just put an xvalve on one of my pumps with the lvl10 and ult and it shoots great, it really ends up being a choose so its up to you and what you want and like.

[athomas]

The X-valve is lighter. The X-valve handles the ULT much better, so you have the ability to have a really light trigger pull on your pump. You don't lose the ability to use the level 10. You just have to use a powertube tip that has been shortened at the back end to allow the carrier to sit farther forward.

[skipdogg]

Weight

[OPBN]

Was going to post up a separate thread, but figured I'll dump this in here. I put together a pump using an X recently and is it anyone elses experience that it takes more pressure to reset the bolt? I've been fiddling with my kit for a couple of days on and off and if I keep the gold spring in, I get occasional semi auto. If I put a shorter spring in, the pressure to reset the bolt seems excessive. Considering I have one pump that I can literally recock with one finger, this just doesn't seem right. Any thoughts?

Setup is an X with an XM15 kit, ULE body. The kit was modded slightly to move the pump block back closer to the frame and the rod was shortened a bit to compensate, but doesn't seem like that should effect the return force of the bolt?

[C_losjoker]

You shorten the both the guide and pump rod? If so wouldn't that make the spring feel harder since you have to compress it just has much but in a shorter/smaller distance?

[OPBN]

You shorten the both the guide and pump rod? If so wouldn't that make the spring feel harder since you have to compress it just has much but in a shorter/smaller distance?

Actually much lighter spring. Its not the pull weight on the pump handle, it's the actual force needed to reset the bolt. I have an AGD kit with an aluminum handle and I can reset it very easily. I have another XM15 kit that has a heavier spring and it is definitely harder to pump, but the resetting of the bolt doesn't seem as hard.

Forgot to mention it's an L7 bolt.

[luke]

The pump setup you sent to me has a miss alignement between the pump handle, pump rod and rail slot, making it pretty stiff even without a valve in it. The rail slot is done to spec, pump rod belongs to the slot so the odd guy out is the pump handle, meaning the hole is drilled incorrectly. Anyway, just wondering if that was the setup that was hardist to reset?

[OPBN]

The pump setup you sent to me has a miss alignement between the pump handle, pump rod and rail slot, making it pretty stiff even without a valve in it. The rail slot is done to spec, pump rod belongs to the slot so the odd guy out is the pump handle, meaning the hole is drilled incorrectly. Anyway, just wondering if that was the setup that was hardist to reset?

It is. I did notice that the pump handle is a little off. It took some fiddling around, but the spring pushes the pump handle back out fine now. I think I should have had you leave the pump rod alone though. It shouldn't make the bolt return harder, but I did notice that on my old XM kit the pump handle is farther forward by the time the bolt is reset on the new kit. And when I take the bodies off and compare where the back of the pump rod sits, it is definitely farther away from the bolt than the old one. I can back the pump rod out a little to get it closer, but then it doesn't leave many threads in. Even with this, the springs isn't totally compressed by the time the bolt sets so its not that.

*** Just to clarify, nothing Luke did is causing this issue and he only did the mods that I requested of him.

[keiko_819]

You just have to use a powertube tip that has been shortened at the back end to allow the carrier to sit farther forward.

do you know about how much to take off?

[captian pinky]

ive always just used the smallest carrier size

[athomas]

ive always just used the smallest carrier size

You run the risk of pushing the carrier and oring back a bit and keeping the bolt stem vent hole exposed which would allow the residual pressure to escape and contribute to inefficient operation.

do you know about how much to take off?

I don't know the exact amount, but if you take an amount equal to or greater than the distance that the wave spring holds the bolt forward, then it will work.