I've been asked to perform maintenance on a Tokyo Marui MP5K HC (high-cycle electric airsoft gun), so I'll proceed with the work.
Let's start by checking the initial state.
*This article aims to provide educational explanations from a mechanical engineering perspective regarding the safe hobby use of airsoft guns.
This does not promote acts of violence, the use of weapons, weapon modification, practical evaluation, or violation of laws and regulations.
Initial state
The exterior is as shown in the following photos.
opposite side
It seems to have been used fairly regularly.
It looks a little wrinkled.
Live-fire performance verification
Next, initial velocity and cycle rate.
The BBs used were Tokyo Marui Bio 2g, and the battery was an ET-1 REDLINE 7.4v, with a fully charged voltage of 8.2V. Measurements were taken with hop-up set to 0.
The initial velocity with a 0.2g BB is 62.54 m/s.
It seems quite low, but given the barrel length of the MP5K, this might be about right.
The catalog states a rate of fire of 25 rounds per second, but research suggests it's actually around 20-22 rounds per second, which is probably normal.
Judging from the initial velocity and cycle rate, it seems a bit worn out.
If you're interested, please also check out my review of the chronograph.
For measuring initial velocity and checking trajectory, white is recommended for better visibility (black is difficult to see). I personally like G&G and recommend them (they're not as accurate as Tokyo Marui, but they offer good value for money).
G&G Bio-Bullets 0.2g
It's inexpensive and accurate, so I use it for a wide range of purposes, from performance testing to airsoft games. It's been my favorite since it first came to Japan (around 2008). It lasts a long time for a biodegradable product.
G&G Bio-Bullets 0.25g
It's 0.25g. I generally use 0.25g BBs when playing airsoft.
Gearbox removal
Let's start disassembling it right away.
First, remove the pin indicated by the red arrow.
This particular model has a metal clip to prevent the magazine housing from opening, so we will remove it.
I wonder if this anti-opening feature is even useful? It's a pain to remove.
The other side is secured with about five bolts.
You can finally disassemble it after removing these screws.
Next, selectorRemove it to match the cicadas.Setting it to semi-automatic mode makes it easier to remove the gearbox.
If you look at the selector from below, you'll see a Phillips head screw.
The selector can be removed by unscrewing it.
Next, remove the motor from the grip.
Please be careful not to drop screws or other objects into the motor.
Also, there is a disc for positioning the motor, so please be careful not to lose it.
Once the motor is removed, pull the upper frame towards the muzzle to detach the frame.
Now the gearbox can be easily removed by pulling it upwards.
It's the other side.
Marui's recent gearboxes are black, aren't they?
Gearbox Disassembly
Let's start disassembling it right away.
In the case of genuine Marui parts, the bolts used for fastening can be removed with a Torx T10 screwdriver.
Unveiling
The anti-reverse latch has popped out.
It's the part in the lower left.
Upon inspection, I found that there was hardly any grease applied inside, and it was completely dried out.
The owner's request this time was to "assemble it using as many genuine Marui parts as possible," so I will basically assemble it carefully using those parts.
Let's take a look at each component.
The gearbox case.
This is the back side. One of the bearings had come loose due to poor adhesion.
This is the gearbox casing on the opposite side.
This is the back side.
Spur gear. This is fine too.
The most important part is the bevel gear. This one's fine too.
Around the switch. It's definitely a bit burnt.
I forgot to take pictures of the cylinder, piston, spring, anti-reverse latch, cutoff lever, motor, etc.
It was basically fine, but the cylinder was a mysterious aftermarket part with a lot of burrs on the acceleration hole, and it also had a mysterious unequal-pitch spring.
The motor is the original EG30000HC.
Chamber area
There's a bolt at the front of the removed upper frame, so if you remove it, the chamber and inner barrel will slide out easily.
I forgot to take a picture of the chamber. It was a chamber assembly with the original 110mm inner barrel.
Since it's getting long, let's assemble it.It will continue to the next.
Tokyo Marui High Cycle Electric Gun MP5K
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