Possible hop up unit issue?

[Pleyland85]

Hi all,

I have a G&P M4 MOTS which is having a feeding issue.

Randomly whilst I’m shooting, it’ll begin to misfeed until I push the mag upwards in to the magwell. 

This happens with all mags I’ve tried including the one it came with. 

Would replacing the hop up unit fix this? 

 

[Adolf Hamster]

are you sure it isn't something like the mag catch causing the mags to not seat properly? is there any visible damage to the feeding tube on the hop?

 

[Callum Hornsby]

Hello,

When you insert the mag does it make a positive click?

When you push it do you push it up and tilt the bottom of the mag forward (toward barrel) or the bottom of the mag backwards (toward you)?

Separate your upper and lower receiver and remove barrel and hop. Is there a spring that is attached to the hop unit at all?

And finally did this problem occur out of the blue or was it after you messed with anything?

Just to clarify I'm no expert I just went through trying to sort feeding issues of my own so have tried about everything in the book  :lol:  and to directly answer your question no a new hop unit probably wont fix your problem but only make it worse (I found out the hard way). 

 

[Pleyland85]

There’s no visible damage and I hear the mags click in. They’ll stop working after a couple of shots or sometimes 100 shots. I give it a little push upwards and it works again for a while. 

I might have to push a mid cap up 2-3 times before I’ve emptied it. 

The rifle has done this from new, I have opened it to check it over since and can’t see any problems. 

I’ve only had it for around a month so I’m speaking to the shop about sending it back. Was just wondering if there was an easy fix without having to courier it back?

I push the mags directly upwards (not forward or backwards). Even just the bit of upwards pressure when I wind up my hi cap does the trick. 

 

[Callum Hornsby]

I'd send it back at least that way your safe as even an easy to fix problem can become tricky and costly.

 

[L3wisD]

Is it worth tightening the wee screw in the mag release button first?

It's highly unlikely, but it's not impossible that it's not tight enough to catch on the mag?

 

[Pleyland85]

It definitely clicks in tight so I don’t think it’s the mag release. 

I’ll send it back to the shop and update the original post when they’ve fixed it for reference. 

Thanks everyone 

 

[Hangtight]

Sounds like the mag isn't high enough in the mag well for the bottom of the hop unit to release the catch on the mag holding the BBs in. Try super gluing a thin piece of plastic to the top of the mag catch to lift the mags a fraction higher in the well.

 

[SCAR_Jester]

I have possibly the same or similar gun.
I have a G&P M4 Sentry with the MOTS receiver.

I had the same issue with 5 mag types and eventually made a temp solution.
I found mags that were tighter going in and then put tape at the back to push it forward. - This did not always work.

Since then I have replaced the G&P hop unit with a King Arms hop unit (I liked it anyway because of the o-rings) and feeding in ALL mags now works fine, no issues, even the loosest mags work well.

I cannot comment if any hop unit will fix your issue, but the King Arms certainly did.

 

[Pleyland85]

Wow! Thanks Corky ?

That sounds exactly the same as mine

 

[SCAR_Jester]

Wow! Thanks Corky ?

That sounds exactly the same as mine

No problem, it saved me having to make larger mags stuffed into the gun that took so much force to pull out. (The only way they would feed).

For whatever reason (maybe the hop unit is longer or the oring holds it up) replacing the hop fixed all issues.

 

[SCAR_Jester]

Before replacing the hop unit I had taken the gun apart from fully built and functionally to every screw out, maybe 11 times for various mods.
Then I took out the hop unit, replaced it with another (same barrel, no change to the gearbox this time), slapped it back together and bam, problem solved.

To clarify the issue,
When you put a mag in and shove it up, you can feel that the mag catch allows up and down movement, enough that the lowest point in this movement is too low for the hop unit to reach the mag.
I used G&G GR16 mags as they fit much tighter, with insulating tape on the back, this tightness stopped the mag from slipping down at all but vibrations and bumping were enough to stop feeding after some time (a little mag slap fixed it for another short time).

I am unsure if the new hop unit fixed it by either:
 

A: Slightly longer so catched the mags at the bottom of their movement in the magwell.

B: The o-ring grips the mag at the top of the movement (however this seems unlikely as I can pull the mag down and it still feeds fine).

So yes I am 100% sure that it fixed the issue, not that there are any screws I can think of that would give feeding issues?

 

[Pleyland85]

Everything Corky said is the same as what I’m experiencing as well. It must be something with these G&P MOTS having a short feeding tube on the hop up

 

[PopRocket123]

I had a similar problem with my G&P. I found that stanag style mags were too loose and fell back slightly, just enough to disengage the release in the mag. I used a bit of plastic glued into the back of the magwell top push them fortresses and that worked for a while. I later swapped my mags out to PTS EPMs and it's worked perfectly since.

 

[Pleyland85]

I’ve replaced the hop up and fired off a mid cap without any problems. Changed mag.. went to try again and now there’s something else wrong. The motor or gears just make a single click when I press the trigger. Nothing happens and the grip feels warm. 

Tried two different batteries and still the same 

 

[Prisce]

The gearbox has locked up. The motor in the grip is getting hot.

 

[Pleyland85]

Thanks! 

I managed to unlock it with the anti reversal latch. 

Now everything is working again.. I finally got to test properly with the new hop up. 

Sadly I still have the original issue.. so I think I’m best ordering a PTS mag and seeing if they work flawlessly. I can always glue a plastic shim on my other mags to make them work as someone suggested.