Tokyo Marui MP7A1 GBB & Action Loading Muzzle

Quick preface: If you’re looking for more info and a shooting demo of the TM MP7, you’re reading the wrong article. If this is what you’re looking for, I suggest you check out (some of) the videos on the Marui MP7 GBB done by a guy going by username KhanSeb on YouTube – he does some very nice shooting demos of many, many Airsoft guns. I’m fairly certain he’s got a few other clips featuring the Tokyo Marui MP7, both demonstrations as well as game play footage as well.

My KWA MP7 GBB is a SMG that I’ve come to respect after shooting it. When Tokyo Marui released their MP7 GBB late last year, I was interested to see how it would be before picking up my KWA. I only recently had a chance to hold one myself, as a few arrived at work a few months ago.

The TM MP7 GBB is in fact a very fun gun to shoot. The kick is noticeably more substantial than the KWA’s light blow back action. Though it doesn’t seem to be quite of an efficient gas system as in the KWA model, I’m hoping to get to try out the legendary TM GBB accuracy and range as it performs in this gun one day soon (I mean, TM puts a similar hop up design into their GBB’s as is in the venerable VSR-10 sniper rifle… how can that possibly go bad?). The space that I plink in at work during down time is not nearly long enough for the hop up to even kick in.

This first photo is the best look I’ve gotten inside the hop up unit thus far (there are video clips all over YouTube demonstrating how to expose the craftily hidden hop up adjustment dial, but asides from that, this angle is the only other look I’ve personally had at the Tokyo Marui MP7 hop up chamber). I didn’t want to take it apart any further than this as this is a gun for sale at work. As much as I want to tinker with it, I’ll leave that up to the person who buys it… oh wait, that might be me (if there’s still one for sale, when I can afford it).


I spent some time at work taking apart the bolt carrier group in the Tokyo Marui MP7, as our demo gun had a blown out loading nozzle – the following article is a result of the photos I took and observations I made while doing that repair.

Only major known problem with the TM MP7 thus far? Loading nozzle blows out on the pressure of Green Gas (or propane).


Front half of the nozzle (which so happens to feature a spring loaded plastic sheath with mock bolt lugs) breaks off of the rear half. This is nothing unexpected though, this is a known issue to happen with a few stock Tokyo Marui loading nozzles when they are used on gasses with higher pressures than HFC 134A – I was expecting this.


Installing a new nozzle isn’t that hard. Performing a field strip to get the MP7 bolt carrier group out is much the same as the KWA – hammer must be cocked, magazine out, remove the stock, pop the 2 pins at the rear of the receiver, and out comes the whole assembly.


Bolt carrier “guide” (for lack of a better term) is a 2-piece plastic affair. I would imagine that someone will eventually produce a steel bolt carrier and/or this part in some sort of fancy metal to increase the kick.


Loading nozzle & nozzle return spring is held in place by this small, bolted-on metal plate with a protruding tab.


Do note that you will need a Torx driver to get this bolt out (also required for removal of the loading nozzle as it blocks off the complete forward travel of the nozzle inside the bolt carrier). Marui usually doesn’t use Torx stuff on their GBB pistols…


Note that inside the MP7 receiver, there are very, very few points for the bolt to get hung up on. Very good design for a fully-automatic GBB – no protruding hammer to get caught on the piston or bolt carrier and cause inefficiencies, especially in a gas-in-mag GBB design that has very little propellant stored to cycle through a whole magazine’s worth of BB’s anyway.


Marui uses a piston cup design in the MP7. Good thing that they didn’t put in a plastic piston head (they are prone to cracking), especially considering the abuse that most players will put their TM MP7 GBB’s through.


New loading nozzle assembly by Action, ready to be installed (note that the small cosmetic mock bolt lugs part is pressed forward by a spring – this spring must be reused from the Tokyo Marui nozzle assembly with the Action set). The material on the Action nozzle, valve blocker, floating valve, and mock bolt piece looks to me like some sort of nylon material – it looks and feels to be more durable for higher pressure gas usage than the stock Marui nozzle. From a first glance, the nozzle body does not appear to be any more reinforced than the stock Tokyo Marui part; that being said, I don’t have an intact TM nozzle to compare to.


The Action floating valve features slightly larger ports. This likely translates to a miniscule increase in muzzle velocity as compared to the stock Tokyo Marui one (same concept as a high flow valve). Without having a stock gun/nozzle on hand that is in opened/fired/disposable (as in I can blow up the nozzle and repair it without incurring any extra cost to my work) condition, I probably won’t be doing a side-by-side FPS test of the 2 nozzles.


I did find an O-ring that didn’t seem to belong… at least, not by the pattern of the usual Tokyo Marui GBB designs that I’ve studied and worked on. I’m fairly certain it serves little to no purpose as a seal of any sort, the only vague idea I have in this regard is similar to the real PRI Gas Buster charging handle venting the excess gas out and to the side – the O-ring around the TM MP7 piston may perform a similar function to vent gas anywhere else other than straight out the back… though I have my doubts about this theory of mine. That being said, the only practical use I can think of for it is to create a rubber bumper for the loading nozzle to slap against, rather than the plastic of the nozzle hitting the cast metal of the bolt carrier directly.


This O-ring seems to cause the bolt carrier group to sit slightly out of battery.

There is another thing I’d like you to look at in this photo – the texture of the plastic. Tokyo Marui plastic (though incredibly durable), does not feel nearly as good as the nylon-ish stuff that KWA/KSC use on their polymer parts. The body of this TM MP7 is no exception to this – this is one of the traits that I feel the KWA MP7 actually clearly beats the TM.


Controls feel and function exactly like the KWA – same size and tension and everything. Only difference is the trigger pull – defined break, reset and slightly harder. Bolt catch releases bolt with upward press (like the KWA), unlike the real MP7 and what WE has supposedly put into theirs.


The magazine output valve is hidden via a plate – interesting concept. Asides from the aesthetic appeal, I’m not entirely sure what this feature is for just yet.


In typical TM GBB mag fashion, there is a enlarged gap in the channel that the follower rides in, to facilitate easier loading of BB’s. This gap starts relatively near to the feed lip, in comparison with other Tokyo Marui GBB mags that I’m familiar with. I did notice that this made staggering the loaded rounds in the magazine much easier, as it gave me much more space to poke at the BB’s to get them lined up right.


Fill valve on the magazine is the standard 2-way TM fill valve. 2-way valves, though more noisy, allow for a much more consistent gas fill as they will fill to the same pressure every time (considering that there is the same temperature and amount of propellant in the gas can).


Chrono results:

  • King Arms Green Gas
  • Tamashi 0.20g Bio-degradable BB’s
  • Indoors, room temperature: approx. 23-25 degrees Celsius






Second chrono session (you can hear the trigger reset after every shot – much nicer than the sloppy KWA MP7 trigger):


4 responses to “Tokyo Marui MP7A1 GBB & Action Loading Muzzle

  • James

    Nice write up, thanks.
    Do you know of any issues with the loading nozzle getting stuck/locked up? Mine has stuck back twice. First time I put a couple of drops of lube in there and after forcing it free it was all good, but happened again at the weekend. Less than 500 rounds through it in total.
    I spoke to another chap who had exactly the same issue, we both bought them from the same place. He changed his nozzle to an Action and it has happened again. We both think it is something to do with the o-ring?
    I’m sending mine back for the shop to look at. Will update with any information I find…

    • juicy

      First off, thanks for reading James.

      I don’t actually own this gun, so I might not be the best person to ask this. At work, I’ve tested roughly 500 shots through this gun after installing the Action loading nozzle set, and have had not had any issues after the repair (and removal of the O-ring).

      Sounds to me like it is probably something to do with a seal somewhere – could be that O-ring or piston cup being dry or cracked, but I’d have to see it to figure it out for sure.

      Please do update me with what the problem turns out to be.

  • phil

    hi! love your blog, been following for awhile from Calgary =)

    just wondering do you have a guide on how to take down the mp7 to the hop up? looking at changing the rubber on mine. thanks!

    • juicy

      Thanks for reading!

      I actually don’t own a TM MP7 myself, I was just playing with one when they were in stock at my job, so I can’t make you a guide for that until I get the chance to open one up further – sorry.

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