Pump mag binding

[OPBN]

He may claim this but from what I can tell the problem is actually that the pump plate tips when using the hitman mod forcing it to bind on the center guide rod.

Could be as well. I wasn't using a hitman mod so I was just going by what I was told in my circumstance. I will say that when I dry fit mine and messed around with it I found it pumped much easier if you kind of pushed up on the handle when pumping it. I could see how the hitman mod would excacerbate the issue.

[BLachance75]

My thinking is that part of the problem is the design of the lower guide rod itself along with some subpar milling. The use of a skinny bolt as a guide rod and the fact that the handle rides on the bolt head is a poor idea. I would have made a little thicker rod and put a hex on the end, similar to what CCM does. All the holes are milled oversize making the kit have wobble, more than I would have liked at least. Mine does slope down like almost all the others and it did bind on a rail that was milled to AGD spec. Rainman milled the channel slightly wider for me and that stopped all binding issues.

If I were to go about building another pump mag I would hold out for an AGD kit or buy a gun that already had one.

[thecroatiansensation]

I am guessing this is the pump that I put together. The reason that the rod is slightly bent in the middle was because it was rubbing against the front lip of the ule body. Since I didn't want that to happen, I bent the pump rod a little down, then back up. It worked fine and pumped smooth as silk when it left my hands.


I have also had an issue trying to use a hitman mod. One thing that you can do is bend the pump rod a little bit to make up for the upwards movement that will occur when you are using the hitman mod (does this make any sense to anyone?). What I have found is that when you use this hitman to pump most of the force is used to push backwards, but since you aren't pushing directly backwards, the back of the pump handle kicks up a little bit and contacts the guide rod. This will cause enough friction to mess up your pump stroke.

I also put a little bit of lube on the guide rod as well. Just tinker with it for awhile and you should be able to get it working right. PM me if you would like any more info.

[BigEvil]

I have never seen a pump kit that there is not at least some issues with. On the RM kit, in addition to the slop, the pump stroke is also ridiculously and unnecessarily long. I have shortened them up and it helped the binding issue mainly because it didn't have that far to travel to get cocked and then bind up. In reality, you can make the pump stroke less than 1/2".

[BLachance75]

Hmm, my kit it only about 1/4" and I didn't do anything to it. I've thought about making it shorter but even now it is almost to short.

[river031403]

This pump in this thread has a short stroke and smooth. I had to sell it to get a football helmet for my son.

[bowcycle]

And most recent shooting video
http://youtu.be/XR7s30tpJCk

Here's your primary problem...never buy anything that involves hairy man-boob!

[river031403]

Here's your primary problem...never buy anything that involves hairy man-boob!

Fresh out of the shower.^^^but as you can see in the video no issues

[SPLATTER-ZONED]

All I can tell is there is just too much play between the center guide rod and the pump handle.....

That's the problem on my gen3 kit. It's binding when using hitman mod even without the pump rod installed.

I don't have the tools to do it, but maybe the handle could be bored and sleeved. Make the tolerance a little tighter.

That being said, my gen2 kit is beautiful, smooth, short, and fast.

I'm going to light my gen1 kit on fire, throw it under a lawn mower, and pour acid on whatever is left. POS.


SZ