BB's not reaching the hop-up nozzle

[Affliction]

I've recently picked up my project gun after about 3 years (fitting a clone gearbox into a G&P m16 body) and I'm mostly finished now. However, I have one major problem: The BB's won't feed into hop-up nozzle.

The gun will fire fine if I hold the gun upside down (gravity causes the BBs to fall into the hop-up) or if I physically push the magazine up towards the loading nozzle while I'm firing. Anything else causes the gun to simply dry fire because the BBs aren't able to reach the nozzle. I've used TM, G&P, and STAR clone mags.

Is there any easy way to fix this problem? Currently I have duct tape stuck inside the magwell, which is holding it up -- however, I'd like a more permanent solution that doesn't look like shit if I were to ever sell the gun.

[03Ghost79]

I'll say you better check your hop-up rubber, maybe its to hard for youre gearbox. Get a soft/thin bucking rubber.

Second is maybe the tappet plate is broken. It will fire still and blow some air BUT maybe the nozzle doesn't move. B/c the tappet plate can't move the nozzle, that's why the BB's can't reach and get stuck in the hop-up.

Happen to me, just now LOL.
Hope the help.

1st check the bucking rubber (soft or hard)

2nd check youre internal gearbox.


03ghost79

[L473ncy]

Possibly a mag catch issue? This is just a wild guess but maybe the mag catch is slightly off spec and doesn't let the mag sit right all the way up therefore doesn't push the BB's up into the hop up unit.

Other thing I'm thinking is that you could shim the mags in a way that it sits "higher" so that it will push the BB's up. When you hold it upside down and it fees, it could mean that the springs in your mags aren't pushing up hard enough and only feeds because gravity is helping it.

[Affliction]

Originally Posted by L473ncy

Possibly a mag catch issue? This is just a wild guess but maybe the mag catch is slightly off spec and doesn't let the mag sit right all the way up therefore doesn't push the BB's up into the hop up unit.

Other thing I'm thinking is that you could shim the mags in a way that it sits "higher" so that it will push the BB's up. When you hold it upside down and it fees, it could mean that the springs in your mags aren't pushing up hard enough and only feeds because gravity is helping it.

That's a good idea. I'll have to strip the mag catch off one of my other guns and see if it will fix the issue. If the mag catch caught the magazine 2-3mm higher, then that would no doubt solve my problem.

Modifying my magazines isn't an option because I have about 20 of them shared between four AR15 variants.

[m102404]

If you hold the mag up and it feeds fine, it's the interface between the bb catch n the mag and the feed tube of the hopup unit. The tube isn't pushing the latch far enough to release the bbs. The first one may go...since when you put the mag in the bbs will spurt out...but subsequent shots are dry because there's no spring pressure behind them.

You can trim the catch..."KA mags not feeding" was a popular search term. It won't hurt any feeding/use of those mags in other guns.

You could also try other hopup units...but it'll be hit and miss.

You could look at your mag catch....if it has a lot of up and down play or if the edge. That engages the mags is not as high as it could be, then trying a different one might work. There's usually very little adjustment there though.

[ryan3311]

Ok so i have been working on my ak/m4 build for a while now and I'm having a similar problem. The body and gear box are an ak ver 3. The mags will sit in the mag well and actually used to feed no problem. Now when i put the mag in it clicks into place but no bbs feed into the hop up unit. It fires just fine upside down so if it was a issue with the mag i don't think it would release any bbs at all and if i take the top off and push down slightly on the hop up it starts feeding. I'm kinda at a loss and I'm just scratching my head and wondering what the heck lol

[DipTwit]

Is it possible your hop-up unit isn't being held in place, or is flexing against the pressure of the magazine from below? It would only take a tiny bit of movement to keep the bb catch in the mag from opening up, there's surprisingly little room for error there. just a thought.

Also double-check that there's enough backwards force from the little spring on the hopup unit, without that the hopup can move around. Usually that just ruins your airseal but I suppose if there were enough tolerance for the tube to move in the top of the magazine it could affect that bb catch opening up too.

[Mobius]

Chek if your nozzle is held back properly and dont prevent the BB to be feeded

[bryanman]

I definitely agree with the magazine not being high enough. Happened in my AK, easy fix. Not so simple on an M4/AR though...

[Rusty Lugnuts]

I modded a lonex hop up to fit in an ics back in the day, One thing i had to do was make the hop up feed tube longer. after that any brand mag fed great

[Zfurlong]

I'm willing to bet it's the tapped plate as well. Some tappet plates have a groove notched in them, some don't. I ran into that issue a while back. A bi of filin and sanding should fix it

[DipTwit]

If it were the tappet plate, I don't see how he would be able to fire a bb by holding the gun upside-down, nor by pushing the magazine up, as he says in his original post.

[Chromey]

Weak Spring in the mag?

[Zfurlong]

Originally Posted by DipTwit

If it were the tappet plate, I don't see how he would be able to fire a bb by holding the gun upside-down, nor by pushing the magazine up, as he says in his original post.

on the bottom of the tappet plate, some have groves and some don't. some gearboxes have little ledges to guide the tappet plate. that's what I was referring to, that maybe its pinched by the gb shell

[DipTwit]

Originally Posted by Zfurlong

on the bottom of the tappet plate, some have groves and some don't. some gearboxes have little ledges to guide the tappet plate. that's what I was referring to, that maybe its pinched by the gb shell

That's good info for sure, but I meant if that were the problem it would probably be a problem even if he held the gun upside-down (he said it fires a single bb fine if held upside-down.) So I kinda think the tappet plate isn't the likely suspect here, that's all.