JG MP5 Hop Up

[ieuanam]

Hello,

 

So I got a JG MP5 SD6 and when I got it, it's hop up was completely non usable and I am asking if I could just go out and buy any old M4 hop and will it fit into this gun?

I want to tech it out as since it doesnt perform to how it was tested, I am going to use it as a project gun even though its a pain to take apart, I hope I will get the first hand experience on teching. Yeah I am a 16 year old noob at this haha but better learn when you're young am I right?

 

Thank you,

         ieuan

[Asomodai]

2 hours ago, ieuanam said:

Hello,

 

So I got a JG MP5 SD6 and when I got it, it's hop up was completely non usable and I am asking if I could just go out and buy any old M4 hop and will it fit into this gun?

I want to tech it out as since it doesnt perform to how it was tested, I am going to use it as a project gun even though its a pain to take apart, I hope I will get the first hand experience on teching. Yeah I am a 16 year old noob at this haha but better learn when you're young am I right?

 

Thank you,

         ieuan

 

Why is the hop up non usable?

 

Unfortunately you can only use MP5 hop units. There are no upgraded ones either. 

[sjhirst]

Funny enough i have just acquired the same AEG, and yes the hop unit is completely out of line with the nozzle making it unusuable.

I purchased a TM hop unit thinking this would fix it but unfortunately it does not, as it looks like its the actual fixing points to the receiver that are out of line.

They, by the looks of it, cause the hop unit to slant upwards and the nozzle rubs against the top of the unit causing constant jamming.

 

[ieuanam]

16 minutes ago, sjhirst said:

Funny enough i have just acquired the same AEG, and yes the hop unit is completely out of line with the nozzle making it unusuable.

I purchased a TM hop unit thinking this would fix it but unfortunately it does not, as it looks like its the actual fixing points to the receiver that are out of line.

They, by the looks of it, cause the hop unit to slant upwards and the nozzle rubs against the top of the unit causing constant jamming.

 

So how do we over come this? Buy an ICS hop or what?

 

13 hours ago, Asomodai said:

 

Why is the hop up non usable?

 

Unfortunately you can only use MP5 hop units. There are no upgraded ones either. 

There must be someone who makes an upgraded one, I mean I cant find any but they make upgrades for the P90 and the MP5 has so many variants and yeah. Is it the same as a G36 hop?

[Asomodai]

Just now, ieuanam said:

So how do we over come this? Buy an ICS hop or what?

 

There must be someone who makes an upgraded one, I mean I cant find any but they make upgrades for the P90 and the MP5 has so many variants and yeah. Is it the same as a G36 hop?

 

There are two MP5 hop designs .

 

The ICS wont work as it uses the alternate design and different slide mechanism. This is only for use with MP5's that have access the hop through the bolt cover. The JG does not have a functioning bolt cover

 

You can buy a replacement hop unit which is the exact same design as the JG but under a different brand, but they are all pretty much made the same. so there is no upgrade. Trust me I looked. 

 

What is exactly wrong with your hop unit? Mine had to be shimmed with better rubber O-rings to stop the lever from moving when firing. 

[ieuanam]

Just now, Asomodai said:

 

There are two MP5 hop designs .

 

The ICS wont work as it uses the alternate design and different slide mechanism. This is only for use with MP5's that have access the hop through the bolt cover. The JG does not have a functioning bolt cover

 

You can buy a replacement hop unit which is the exact same design as the JG but under a different brand, but they are all pretty much made the same. so there is no upgrade. Trust me I looked. 

 

What is exactly wrong with your hop unit? Mine had to be shimmed with better rubber O-rings to stop the lever from moving when firing. 

Right so since I got this replica from Gunfire, it says it shoots 340fps, It didnt it shot like 200 fps and without hop it shot to about 8 meters then drops straight to the ground, with the hop on, less than that, 5 meters and straight to the ground. I did the spring setting at the back and got 300fps and got my hop to work to 20 meters without dropping. However every third shot, the bb flies straight to the floor and its so unreliable and unstable. Since this is from Poland, there is no point in sending it back and as I said before I am a 16 year old who is new to teching. I would have teched out my Nuprol Pioneer Defender but haha Nuprol lol so no and yeah I got the MP5 since it was £80 new from Gunfire

[Asomodai]

39 minutes ago, ieuanam said:

Right so since I got this replica from Gunfire, it says it shoots 340fps, It didnt it shot like 200 fps and without hop it shot to about 8 meters then drops straight to the ground, with the hop on, less than that, 5 meters and straight to the ground. I did the spring setting at the back and got 300fps and got my hop to work to 20 meters without dropping. However every third shot, the bb flies straight to the floor and its so unreliable and unstable. Since this is from Poland, there is no point in sending it back and as I said before I am a 16 year old who is new to teching. I would have teched out my Nuprol Pioneer Defender but haha Nuprol lol so no and yeah I got the MP5 since it was £80 new from Gunfire

 

 

You get what you pay for is what I would say and the risk you take from buying overseas if you don't want to send it back. 

 

Without opening it up I couldn't tell you what's wrong with it. Best open it up first and see if there isn't anything obviously wrong with the hop unit before buying a replacement. It could just simply be a misaligned nub. 

 

They aren't the easiest to take apart so be warned, very easy to lose springs and such. 

[ieuanam]

Just now, Asomodai said:

 

 

You get what you pay for is what I would say and the risk you take from buying overseas if you don't want to send it back. 

 

Without opening it up I couldn't tell you what's wrong with it. Best open it up first and see if there isn't anything obviously wrong with the hop unit before buying a replacement. It could just simply be a misaligned nub. 

 

They aren't the easiest to take apart so be warned, very easy to lose springs and such. 

Thing is I have opened it and I have changed the inner barrel to a much longer one and since then I have not fired it. I didnt see what was wrong straight off and what do you think I should do about it?

 

[sjhirst]

This image hopefully gives an idea of what was wrong with mine. It doesn't show it as much as it does for real.

I came about this as I was fitting an Inferno engine into it and the nozzle would fire then just jam.

Gearbox perfectly aligns but the unit itself...bad day at QA?

You can gouge out the screw holes of the hop units screw holes to try and align it better. 

Hopefully this isn't your issue, but thought i'd highlight it for future reference.

[Asomodai]

3 minutes ago, ieuanam said:

Thing is I have opened it and I have changed the inner barrel to a much longer one and since then I have not fired it. I didnt see what was wrong straight off and what do you think I should do about it?

 

 

So you've changed the inner barrel to a much longer one but not change the cylinder to match it? You will get undervoluming issues. 

 

Did it work correctly before you changed the barrel? I think you need to tell us exactly what you have done and what the FPS was before and after each change. 

[ieuanam]

1 minute ago, sjhirst said:

This image hopefully gives an idea of what was wrong with mine. It doesn't show it as much as it does for real.

 

Is it facing upwards?

Just now, Asomodai said:

 

So you've changed the inner barrel to a much longer one but not change the cylinder to match it? You will get undervoluming issues. 



 

Did it work correctly before you changed the barrel? I think you need to tell us exactly what you have done and what the FPS was before and after each change. 



I have not used the gun since after changing the inner barrel. When I sent you what happened  to the Hop-Up, that was before anything had happened to me taking apart the gun and I do admit that lining up the upper receiver was a pain as where the hop lies was where there was a gap without screwing it down. I'm thinking of re-opening my gun in a minute and I might send a picture of it

[sjhirst]

yes, the hop uint is going up in the direction of the arrow. it does not sit horizontal with the receiver.

Looking down the hop unit, there is an extra groove as highlighted in the square. I thought this might be where the nozzle was hitting it due to it being mis-aligned.

I dunno, perhaps its supposed to be like this? but it just doesnt seem right to me!

 

[ieuanam]

Just now, sjhirst said:

I dunno, perhaps its supposed to be like this? but it just doesnt seem right to me!

 

None of this seems right to me either

[sjhirst]

Unfortunately with it being a TM clone, you have to strip it down the same way which means everything off and the receiver splits in half- a pain!

If you do do it, take your time and photo where everything goes if needed.

Hopefully it is an easier fix.. Good luck

 

ah, I just re-read and see you've already had a go at it. Not so bad then

[ieuanam]

Just now, sjhirst said:

Unfortunately with it being a TM clone, you have to strip it down the same way which means everything off and the receiver splits in half- a pain!

If you do do it, take your time and photo where everything goes if needed.

Hopefully it is an easier fix.. Good luck

I've striped it down before and it is such a pain, have you fixed yours?

[sjhirst]

No haven't fixed it, I just cant be bothered to be honest.  I put the inferno back into the specna arms which is an absolute doddle compared to that lol.

I'll use it for spares if ever needed by me or anyone wanting bits that i see on the forums.

A costly mistake but hey, thats airsoft for you. ( I bought mine from the UK)

[ieuanam]

1 minute ago, sjhirst said:

No haven't fixed it, I just cant be bothered to be honest.  I put the inferno back into the specna arms which is an absolute doddle compared to that lol.



Ah thats fair enough, I will try to get mine working so I will post pictures later, thank you everyone for helping though

[Samurai]

Probably the gearbox was put back misaligned. Not placing the wires back correctly can result that.

[ieuanam]

1 hour ago, Samurai said:

Probably the gearbox was put back misaligned. Not placing the wires back correctly can result that.

This was before I took apart the gun (the reason why I took it apart in the first place haha) 

6 hours ago, sjhirst said:

yes, the hop uint

 

Here is my hop up

[sjhirst]

looks good to me. I can see that it runs parallel to your receiver so thats one less issue to worry about

[ieuanam]

2 minutes ago, sjhirst said:

looks good to me. I can see that it runs parallel to your receiver so thats one less issue to worry about



nice 

[ieuanam]

Okay, So I have completely rebuilt the gearbox and it runs good however I had a problem with the piston tooth on the SHS 14 Teeth Piston with teeth 1 and 2 getting stuck with the SHS 13:1 sector gear. I resolved this by short stroking the teeth on the piston.

 

The problem I have with the bbs dropping is still here but a lot less. In Semi I get 150 fps and the occasional 250 fps with the 250 fps flying how it should.

 

Go into full auto and thats another story, I'm getting 250 fps with every shot and all the bbs fly out how it should but with the occasional 1 bb going straight to the floor.

 

I have no clue what is up, I might change the spring to a harder one that I have laying around, I'll try the compression test.

 

I am thinking that it probably is a barrel/hopup issue and I don't know how to test to see if it is a hopup problem.

 

@sjhirst Have you fixed your MP5?

[sjhirst]

Hi.

No its all sitting in a parts box lol.

[Asomodai]

7 hours ago, ieuanam said:

Okay, So I have completely rebuilt the gearbox and it runs good however I had a problem with the piston tooth on the SHS 14 Teeth Piston with teeth 1 and 2 getting stuck with the SHS 13:1 sector gear. I resolved this by short stroking the teeth on the piston.

 

The problem I have with the bbs dropping is still here but a lot less. In Semi I get 150 fps and the occasional 250 fps with the 250 fps flying how it should.

 

Go into full auto and thats another story, I'm getting 250 fps with every shot and all the bbs fly out how it should but with the occasional 1 bb going straight to the floor.

 

I have no clue what is up, I might change the spring to a harder one that I have laying around, I'll try the compression test.

 

I am thinking that it probably is a barrel/hopup issue and I don't know how to test to see if it is a hopup problem.

 

@sjhirst Have you fixed your MP5?

 

Are you using mid caps or high caps?

[EDcase]

Fitting a stronger spring would be a bad idea as that would likely break something.

 

If the hop unit is out of alignment that could explain those inconsistencies.

What about filing the hopup attachment holes in the direction to counter the incorrect angle.  Hard to explain but make the holes longer so the hop can be rotated a bit until the screws are tightened (maybe with some blue locktite)