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Ollllld TM MP5 & JG MP5K questions

J

Jimbodini42

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Hi,

So I’ve got a 18+ year old Tokyo Mauri MP5 and took it out for a skirmish last weekend with new batteries and a bit of a clean. It actually does ok! 
However it was only around 230fps on .20g bbs, it’s range quite short at around 30m

max and it’s ROF significantly less than other people’s AEGs. 
I’m no techie whatsoever but I’m a PE teacher and I think I’m going to have a lot of time on my hands when schools inevitably close so thinking of learning! 
 

What would be worth doing on it to get some improvements? OR WOULD COST END UP BEING SAME/MORE AS A NEW AEG? Would like to turn it into a hard hitting CQB weapon but site I often go

to is outside and CQB so getting new motor for increases ROF would also be beneficial. 

I’m actually assuming the hop rubber is ok as it was always looked after anyway. 

 

—————- Tech advice needed ——-

JG MP5K- picked this up for next to nothing and loved size for indoor CQB so I want to persist with this. 
 

However - 

1) It regularly got stuck while in semi - pulled trigger and nothing. Put onto full auto, burst, cleared, back to semi and worked. Any ideas on how to solve this? Take it is something to do with gears not fully turned? 
 

2) Fire selector switch was loose so I tightened it. Lent it to a mate during the day and he’s lost the switch - any innovative or bright ideas to do more than tighten screw so it doesn’t fall off again when I replace it? Any ideas for a cool replacement that’s not gonna cost me £12 to get a new one? 
 

3) Is it worth doing internals on it? Same sort of stuff suggested and needed as with TM one above??? 
 

Many thanks all for any input. 
 

Regards 

 
TM: was it unused for a long time? Change the O ring on the piston and the hopup rubber.

JG: 1: make sure you pull the trigger all the way every time and use a good battery. 3: checkup, clean and relube

 
Hi - thanks for reply. 

Yeah, wasn’t used for 15 years I reckon. 
 

Any brands or places or sizes I should know about regarding O ring and hop rubber? 
 

For the K - by relube (making sure) do you mean the gears? 
 

Thanks my Man! 

 
Rubber can degrade and become brittle left to its lonesome for many years, so I would possibly think about a new hop rubber as well.. you mention that it was well looked after, but how long ago was it last checked?

And if you do go that route, you may as well go for something like a maple leaf and flat nub to get a little range, accuracy and consistency boost (go for maple leaf 50. (green) if your on the lower side of FPS)  

If you swap out the spring and are hoping to use it for woodland and CQB, you probably want to tune for around the 320-330 mark (most cqb sites allow up to around that, while still being decent enough for ranging outdoors) - so an M95 or M100 spring would probably be what you are after, however your seals in the gearbox, barrel and hop may need to be optimized to reliably hit the upper limit of that FPS target.

And yes, a nice new motor would definitely help, an SHS or ZCI wouldn't break the bank but perform fairly well. A mosfet would also help with ROF, trigger response and switch protection, though you would definitely need a tech to install that for you, unless you go for a pre-soldered switch assembly unit. A mosfet would also allow you to use a higher voltage battery - if it's an old TM I assume you are on an 8.4v nimh?

When @Samurai mentions relubing, he almost certainly means the seals as well as gears, getting some nice silicone gel/grease on the piston and cylinder heads and inside the cylinder is important. The standard sizes for piston head Orings is 19mm with a thickness of 2.5mm I believe. 

 
Last edited by a moderator:
Hi

Great advice - thank you. 
Yes using 8.4v Niamh with it and checked the hop rubber the other day - seemed ok. Though don’t really know what it’s supposed to look like, feel like etc? 
 

Anywhere that you recommend as a place to get the parts from? 
Just for my understanding - 

Go for a maple leaf and flat nub to replace the hop. 
Then a M100 spring 

and I should see some improvements? Then, perhaps need to sort seals on gearbox, barrel and hop to get the most out of the new spring and hop? 
 

Cheers! 

 
Jimbodini42 said:
Hi

Great advice - thank you. 
Yes using 8.4v Niamh with it and checked the hop rubber the other day - seemed ok. Though don’t really know what it’s supposed to look like, feel like etc? 
 

Anywhere that you recommend as a place to get the parts from? 
Just for my understanding - 

Go for a maple leaf and flat nub to replace the hop. 
Then a M100 spring 

and I should see some improvements? Then, perhaps need to sort seals on gearbox, barrel and hop to get the most out of the new spring and hop? 
 

Cheers! 
Click to expand...


A stock TM rubber should feel relatively soft, though not gel like, it shouldn't feel at all hard or brittle - that being said, it is absolutely worth your while switching to the maple leaf, for all intents and purposes the maple leaf is an out of the box flat hop solution so it will give you that little boost is accuracy, range and consistency (honestly some times not so little!).

There are actually very few  aftermarket MP5 hop units, though actually the stock one should be fine so long as it doesn't have any cracks or other obvious faults.

Inner barrel... yeah not a bad idea too, ZCI 6.02 wont break the bank but is decent ?

So long as you install the hop and barrel components correctly you should almost certainly see a pretty decent improvement.

A lot of people on here use https://www.ak2m4.co.uk/ and the owner @ak2m4 is also here on the forums, so you can PM him when you aren't sure about the parts you might want.

Maple leaf rubber:

https://www.ak2m4.co.uk/internal-parts/hop-up-buckings-nubs/maple-leaf-macaron-50-aeg

Flat nub:

https://www.ak2m4.co.uk/internal-parts/hop-up-buckings-nubs/omega-nub-soft-70-gear-parts

Inner barrel:

https://www.ak2m4.co.uk/internal-parts/inner-barrels/zci-inner-barrel-229mm

M100:

https://www.ak2m4.co.uk/internal-parts/springs/guarder-sp100?sort=p.price&order=ASC

Lubricants:

https://www.ak2m4.co.uk/index.php?route=product/search&search=grease

the 5ml for seals/Orings and the 10ml for gears and other hard contact points.

Replacement piston head O-ring: 

https://www.ak2m4.co.uk/piston-head-o-ring-viton-19mm?search=o-ring

All of the above is currently in stock by the looks of things.

 
Last edited by a moderator:
Yep all that is still in stock, but deliveries into the UK from Chinese suppliers are being hampered now by the problems in the EU.  

 
Jimbodini42 said:
You sir, are a legend. 
 

Thank you ? 
Click to expand...


No worries bud, lots of disassembly guides on youtube for the MP5 and the gearbox when you're finally ready, but ofc any issues let us know and will help out as best we can ?

 
Last edited by a moderator:
Going to watch this topic with interest. I bought a JG MP5K to "tinker with" last year and I still haven't fired it in anger? It has very much been a labour of hate so far.

It's pretty much all in one piece now except for the trigger spring, that is an absolute nightmare.

 
Nunfa1 said:
Going to watch this topic with interest. I bought a JG MP5K to "tinker with" last year and I still haven't fired it in anger? It has very much been a labour of hate so far.

It's pretty much all in one piece now except for the trigger spring, that is an absolute nightmare.
Click to expand...
I loved using it at HQ airsoft the other week. Cleared rooms so quickly and smoothly. Felt lighter and so maneuverable. 
 

Just jammed on semi so often. Also low ROF on both semi and full.
 

Also when it was on crono the FPS was quite low - definitely some kills I would have got but don’t think they felt it! So certainly think it needs a tune but could also be worth it! 
 

I’m also going to work on some sort of adaptation of a 3 point sling to get it tight to my body as I plan on using it more often but as a secondary and leave my SOPMOD outside when breaching 

 
mzjango said:
A stock TM rubber should feel relatively soft, though not gel like, it shouldn't feel at all hard or brittle - that being said, it is absolutely worth your while switching to the maple leaf, for all intents and purposes the maple leaf is an out of the box flat hop solution so it will give you that little boost is accuracy, range and consistency (honestly some times not so little!).

There are actually very few  aftermarket MP5 hop units, though actually the stock one should be fine so long as it doesn't have any cracks or other obvious faults.

Inner barrel... yeah not a bad idea too, ZCI 6.02 wont break the bank but is decent ?

So long as you install the hop and barrel components correctly you should almost certainly see a pretty decent improvement.

A lot of people on here use https://www.ak2m4.co.uk/ and the owner @ak2m4 is also here on the forums, so you can PM him when you aren't sure about the parts you might want.

Maple leaf rubber:

https://www.ak2m4.co.uk/internal-parts/hop-up-buckings-nubs/maple-leaf-macaron-50-aeg

Flat nub:

https://www.ak2m4.co.uk/internal-parts/hop-up-buckings-nubs/omega-nub-soft-70-gear-parts

Inner barrel:

https://www.ak2m4.co.uk/internal-parts/inner-barrels/zci-inner-barrel-229mm

M100:

https://www.ak2m4.co.uk/internal-parts/springs/guarder-sp100?sort=p.price&order=ASC

Lubricants:

https://www.ak2m4.co.uk/index.php?route=product/search&search=grease

the 5ml for seals/Orings and the 10ml for gears and other hard contact points.

Replacement piston head O-ring: 

https://www.ak2m4.co.uk/piston-head-o-ring-viton-19mm?search=o-ring

All of the above is currently in stock by the looks of things.
Click to expand...
Hi

just quick Q as I’m thinking I might do each bit in turn, see what it’s like and then add more if A I’m not ruining the gun through poor workmanship and B looks like I’m actually able to do the work! 
 

- can I just change the spring & nothing else and it’ll all fit and work? (Albeit perhaps not optimised)? - but still should be more potent than before? 
 

- same question but with the hop rubber? Need to change the hop rubber and the nub at same time?? 
 

thanks! 

 
Jimbodini42 said:
- can I just change the spring & nothing else and it’ll all fit and work? (Albeit perhaps not optimised)? - but still should be more potent than before? 
 
Click to expand...


Yes you could, though while you are doing that you may as well lube up the seals on the piston and cylinder O-rings.

Jimbodini42 said:
- same question but with the hop rubber? Need to change the hop rubber and the nub at same time?? 
 
Click to expand...


These two items mate together; no real point in using either on their own - install them together ?

 
So...

I went to do the hop up and spring change on the JG MP5K thinking this is what I’d likely use more and also I’d be less heartbroken if I knackered it in the process over my ancient and much loved old TM MP5A5. 
 

Got it all open, disassembled every part of the gun for learning experience then got to the gearbox... 

It has a metal slide on top that wouldn’t budge and caught on every cm of it as I eventually slid it off. In doing so, the whole gearbox sprung open and bits went everywhere. 
 

Ive been watching loads of videos and I’ve just about worked out what each piece does. 
 

However, one thing I’ve noticed is that the new spring is slightly longer than the previous one - do I still put this in??? Or does it need trimming down? Guessing if trimming down that’ll lose energy!? 
 

Asking before I have another go at putting it all back together!! As don’t want to try and force it in for ages for no reason! 
 

 
The length doesn't matter.

Also, next time slide the top off before undoing the screws.

Good luck putting it back together.

 
Good luck with the re-build. 

Whilst its in bits, could I ask a favour? Could you take a picture of the fire selector cam? I can't seem to find mine and I'm having trouble finding a spare. Thanks.

 
Great, thanks. It's the circular one with the teeth. 

Be sure to let me know how you get on with the trigger spring...

 
Having to have a break! 
 

IMPOSSIBLE to get the trigger spring back in. Can barely fit it back in without spring never mind with spring pushing back. 
 

spring doesn’t seem to line up properly to me. 
 

ANYONE CAN YOU HELP?? 

 
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