Shell Kit MP-5K Rebuild...( or...Double mag, ain't no drag!)

[BME]

So, i got around to pulling the MP-5 double mag kit apart.
This was the kit released around 2017 ( im guessing).

The kit was an empty shell, designed to take a drop in gen8 gearbox.
It has the double stacked, linked magazine.

It always was a great little performer… i got it from M4A1 from memory.
It required a 11v battery to run, it did 270-280 fps when i got it.
Impressive, for such a short barrel, and great accuracy too.

Recently, the fps had dropped to 240 ish…and its also had feeding issues.
Before teardown, it wasnt feeding at all.

I pulled the mags apart, quick clean, all nice and clear.
The mag was feeding gels up and into the t-piece…just not firing…?

anyway , pulled it apart.

Yep, its got a ported cylinder on it, and nylon gearbox.

[BME]

Pulling apart further revealed a few things…

The spring retainer assembly wasnt sitting right.
The spring appears to be a m100 (should be ok for limited use in nylon), but it had twisted in its mounting.

I reset it back to proper position, and test fired…it eventually worked its way back. It gets to this position and stops.

I guess thats what it does… it remains retained…A shorter M90 would provide less twisting force… but also less fps.
Its lasted this long…

[BME]

Pulling it down further revealed…Nylon everything…

Nylon pinion gear, main gears, piston , ladder etc etc.
No signs of wear, all working well, so i’ll leave it for now.
As i said, minimal use, and its all worked well so far.

Maybe when i build up a singularity gearbox, ill use metal everything and transplant it then.

Ive been told, the singularity gearboxes only accept polycarbonate motor shells?? is that confrimed.? Nylon ones wont fit into a singularity cage?

Anyway, i think i found the problem…

Nozzle tip is loose, and coming off.
Can you reglue these back on successfully with araldite.?
Or best to just get a new one.?

I’m assuming if the nozzle isn’t airtight, it dumps all the air out around the nozzle, not through it…hence gel failure to launch ( despite air exiting from front of the barrel).

Original oring is still pretty good.
Air seal in fantastic.
Cylinder head is glued on, and seal with the green oring is still airtight.

I’ll change the o-ring anyway.

So, that’s the plan…

New oring.
Grease up gears.
New nozzle.

reassemble, and see if it works…!!

Time for a parts top up, shop…!!

[BME]

xforce nlakes dont have a gen8 nozzle…

Can you successfully re-glue the nozzle back on.?
Will araldite hold it.?

[Friendly_Fire]

I wouldn’t use Araldite to reglue a nozzle rubber back on. I usually give the nozzle spigot a good clean with isopropyl alcohol or shellite and use a small dab of CA glue (superglue) to secure the rubber. Get it right though… once the rubber hits the CA it’s stuck there.

It will seal and function if the rubber’s not glued on, but sooner or later it’ll come off and then… no bueno.

X-Force don’t have any Gen 8 nozzles?? Bloody savages. I’ve got lots of them if you get stuck.

The easy way to fix that janky piston spring is to use a metal Gen 8 spring retainer, they usually have an M4 or M5 thread tapped into the end of them. A flat steel washer screwed to the back of the retainer will stop it from moving around and will hold your spring in alignment with your piston.

Which is why CYMAs are so good with their quad lug arrangenent for the spring retainer instead of just two for the Gen 8s… and some other V2 boxes. Holds everything square and doesn’t allow any movement of the retainer which can cock your spring on an angle.

[BME]

I wanted to get it back together, so i did a xforce southside dash…

got the new gen 8 nozzle, and spare t piece for the HLF UMP45 repair…

Vas mentioned that he may bring in some Snow wolf thompsons…

All Metal, and real wood…!
Metal mags already done, from pulse rifles…

[shadow187]

@BME

Vas mentioned that he may bring in some Snow wolf thompsons…

[BME]

WAT should also have their container landing next week…

How long it takes to clear customs…unknown…

Has the M1 Garand, M14, M1919 etc…

Hopefully sooner, rather than later…

[BME]

Hmmm. interesting…

Blaster had stopped feeding before the teardown.
Gels were feeding up the magazine, into the t piece, but nothing was coming out.(mag powered)

Now, post rebuild, gearbox is working fine, but gels are not feeding up into the magazine.
Mag tests ok with external 9v battery.
Cleaned up (shiny) connectors with vinegar.
Still no power.

Added some alfoil into the recessed mag terminals, and bent the springs from the blaster down a bit. Mag is now powered, gels are feeding and shooting…but only like 50 fps.

They fire out of the barrel, and go about 3-4 m.

What could it be.??

[Friendly_Fire]

Probably something amiss with the assembly. Most likely t piece location, at a guess.

Is there a spring in front of the t piece pushing it back and seating against the gearbox?

[BME]

Hmmm…the t piece did seem to be seated properly…
Maybe pull it all apart, and start again…
2morrow…

[BME]

This is the photo before i pulled it apart.

It went back together, the same way…( AR latch not withstanding)

[Friendly_Fire]

Looks like a Gen 8 alright.

Nothing in there apart from the tappet spring would cause any problems… and the t-piece is located in the gearbox shell.

Must have been having a brain fart when I started rattling on about springs earlier… been a while.

The obvious suspect would be the nozzle being too short to seal against the gel. Maybe the rubber’s too short or the t piece is wrong.

[BME]

I’ll do another pull apart 2morrow…

I seem to remember the guy saying, they were a bit twitchy to assemble.

You slide the gearbox into the upper shell, and push/pull forward to find the right spot.

Too far forward, and the mag wont go in. To far back, same problem.
You can also rotate a bit, left and right…that might affect terminal position.

Then you have to put the grip on , rear on and lock it in place.
Fun , fun…

[DocBob]

This is really doing my head in that I can’t remember/find the brand of these rare old Blasters.

I was certain that they were HQI, or HQ Industries… something like that, but I’m hoping that @RokSolid can clarify this, as these are the Blasters that I have all the spare single and double mags that I’m still yet to send out to you and Rok @BME… which I’ll have to pull my finger out now you have actually started working on it!

[DocBob]

P.S. @BME, still have my one of these rare beasts that was saved for my collection, non functioning of course, but certainly all there if you need any reference pics for your rebuild.

[DocBob]

@BME

The spring retainer assembly wasnt sitting right.

That has always been something that I have commented about regarding the major issues with the old twin lug horizontal spring retainers, too much space to allow the spring to tilt into the gear area, and if it gets really bad, will catch on the back of the piston and destroy the whole gearbox

Vertical 2 lug retainers mean that the spring has very little room to tilt side to side in the mainspring sections within the gearbox, eliminating the threat of locking up pistons, but will still cause wear and tear with constant use.

I celebrated when the very first 4 lug and 4 lug cross pattern spring retainers were eventually designed an released, eliminating all the previous issues.

But prior to this, I’m sure that a few here would remember the old remedy we did back in the day by fitting a threaded spring retainer to these gearboxes, then using a washer (or 10c piece with a hole drilled through it!) to then allow to run a bolt and sandwich the whole assembly firm to the rear of the gearbox.

Old memories are coming back seeing this old project!

[BME]

HQI does ring a bell…
I bought the kit, a gearbox, some upgrades (at the time) and all assembled, from M41A.
Would have to have been around 2017 or 2018.

As I said, it did a solid 280 fps out of the box.
The only MP5k available, for a long time.

I remember the guy saying they were a bugger to get working.
Fitting the last , rear push pin is a bugger.

You need to push it together with great force, rotate the rear in, with one hand, and push the pin down hard, with the other….

I did a practise run, before I pulled it apart.

That final “click” , is hard won and satisfying…!!

[DocBob]

Yes it was 2016/2017 and were the very first MP5 ever available on the market, but were only available as an empty shell in kit form, because even then these were VERY expensive as a kit, whereas they thought that if they charged double for a complete ready to fire version… nobody would buy them.

This is what makes them so rare, a very limited number brought into Australia to gauge the market because of their high cost, and as it turned out, yes, bugger all were sold other than the few wealthier and more experienced hobbyists out there in what was basically an unknown hobby at the time.

[BME]

It was even before the Nwell MP5k.

Had that been out first, that probably would have scratched my MP5k itch….

Yeah, I remember it being expensive at the time…

Even more so when I was living off my savings, going through uni again…!!

The original green oring stood the test of time pretty well…!!