Cerbo Knight

Tanaka M40 takedown (VERY picture heavy)

13 posts in this topic

To all, my Tanaka rifle was playing up from when I bought it so I decided I'd clear some room on my desk and take the thing apart. So I did, and after I familiarised myself with it I decided it would be a good idea to start on the takedown guides I've been thinking about, so without further ado I only give you one warning. This is going to be picture heavy.

 

NOTE TO MODS: I may have to double post (many times?) to get all of the pictures in, not sure about the picture cap for posts on this forum... Thanks.

 

Also a note to all: Yes, my fingers/finger nails are incredibly dirty from taking this rifle apart not 10 minutes before these pictures were taken, and I guarantee if you're taking your rifle down for the first time yours will be even worse than mine. Just a point to remember ;)

 

So first of all, we're going to start from the very basics and I'm going to cover points that I think are important while I do this guide, starting with the fact that my M40 isn't standard. That much is quite obvious, as I've got a G&G heavy barrel installed and not the standard one so from what I've heard the standard one isn't a free floating one like mine. The standard barrel should have the front sling stud(s) to help secure it. Now the G&G heavy barrel is truly a free float, as it's only attached to the receiver, I'm not going to go into an accuracy debate about Free float vs. Not, it just is free float. Also another thing you'll notice when I get to the bolt, is that I have the PCS bolt, and you may not, and for the most part this won't affect you at all for this guide, it just means that your main screw in the bolt will be longer and you won't have the PCS valve.

There's also some differences in my trigger mech, I've only got one trigger spring in there. Doesn't affect the performance or stability of the rifle, just means I only have one spring. My KJW has the exact same setup, but if you only have one trigger spring too, then you've got to make sure it's on the same screw as mine. This is very important, or your rifle won't function properly.

 

Ok, now onto the actual rifle. First, it's a good idea to remove any optics you may be running. It's just to make handling the rifle easier but most people would likely do this anyway.

 

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Next to go is the magazine

 

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Then you should locate the bolt release button inside the trigger guard, and take out the bolt. It's not necessary, it just saves you having to do it later.

 

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Now we actually get down to taking the stock off, the first bit you're going to need to do is unscrew the sling stud(s) unless you're me in which case you have a non standard barrel

 

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Next goes the allen bolt in front of the mag

 

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Then the allen bolt behind the trigger guard

 

IMG_6257.jpg

 

Once you've taken these two bolts out, you can just pull the trigger guard off. Lube/clean the mag release if it needs it, and if it doesn't come out don't force it, just wiggle it out. It will come out eventually.

 

IMG_6258.jpg

 

At this point I took my hop wheel out, but you can do this now or later as you please. It just screws out, turn it like you're turning off the hop and just keep going, there's no retention mechanism at all.

 

IMG_6252.jpg

 

Congrats. You've now taken the stock off and you can get down to the action, barrel and hop up.

 

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First comes the hop, your barrel will most likely just screw off, if you look closer you'll see the threads that my barrel is attached to. If it has screws in place, then unscrew them.

 

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once the barrel is unscrewed, the retaining 'nut' will come away from the receiver, bringing the inner barrel and hop up with it. Put the receiver aside because at this point you're not going to be touching it.

 

IMG_6262.jpg

 

The retaining barrel 'nut' and hop 'brace' will just slide off of the inner barrel, you can put these aside and you're left with the hop chamber, rubber, and inner barrel. I'm planning to replace the stock hop chamber with a Kings Arms or Spartan Doctrine chamber, so I can use VSR barrels and buckings. Much more effective than the stock hop up (especially mine, more on that later).

 

IMG_6263.jpg

 

Make sure you unscrew the retaining grub screw in the hole pictured, it'll tear your bucking to bits if you don't. The other hole is for your nub.

 

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So the main reason for my taking apart this rifle was that my hop was acting like it was fixed. and this is why! No wonder. The makeshift nub was so ruffed up and sharp it had just torn right through my stock bucking. This is why people shouldn't bodge job their gas guns and sell them without checking them first! Oh well, the whole rifle was only £100... With a scope, bipod and all you see in this guide. :D

 

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This being the inner barrel and stock hop up chamber, without the bucking on so you can see the cutout for Tanaka Barrels.

 

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Now we're going to move on from the barrel and hop up, and go onto the receiver. You can now assemble the barrel if you so wish and are done with it.

 

All you need to do to get the trigger mech out, is punch two pins out. The first being here;

 

IMG_6269.jpg

 

The second is here, but you can pull it from this side because it has almost a nail (think hammer and nails) type head on it;

 

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Now all you're left with is your bare bones receiver, put this aside to avoid accidental damage by knocking the damn thing off of your work space. Almost did that myself, but it was balancing off of the edge of my desk...

 

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Usually, all you need to do maintenance-wise is drop some silicone oil or white lithium grease (thin) into the mech, and pull the trigger a bit.

 

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For those who have trigger issues, never fear! I'm here to help and I know all about the trigger.

First start by taking this screw out, and carefully removing the spring that it holds down. Dont bend this or it WILL break (my first one did, lucky had my KJW's one handy)

 

IMG_6278.jpg

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SECOND PART! :D

 

Then move onto removing the C-clips pointed out by screwdrivers in this picture

 

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The C-clips for the pins you just removed will allow all the external parts from the trigger mech to come off. Make sure you don't lose the metal ball from the safety :) There's also two screws on the mech, you'll see them. They're crossheads, so think about replacing them before they round off their heads.

 

IMG_6280.jpg

 

The spring I'm pointing to was grinding against something and making an irritating noise, and isn't needed so I took it out. You can do the same if you want to, less parts in the thing means less to go wrong as well.

 

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I took this opportunity to spray white lithium grease liberally on the mech. I suggest if yours was as dry as mine was, that you wipe it all clean and re-grease it.

 

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You can put the two halves back together, and get the sear spring and place it like this;

 

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Then goes in the valve knocker

 

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And finally the sear itself.

 

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And secure with that strange little brass tube. :P

 

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Now put the safety back on, all it needs is the holes aligned like in the picture and the metal ball goes straight in, as does the pin you took out during disassembly

 

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Put the metal ball's cover on it, and you can put the securing pins back in and the C-clips back onto the pins. Then do up the screws you took out, or whichever way you want to assemble it, it doesn't really matter.

 

IMG_6291.jpg

 

Now this part is annoyingly tricky until you get the hang of it, you need to press the spring down into the gap and push the pin in, while holding down the sear on the other side of the receiver. I didn't install the trigger mech so you could have a clearer picture, you will need to install the trigger mech before this though.

 

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Here's the spring where it's meant to be. (close to it)

 

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Now install the trigger mech, and push in the securing pin. It shouldn't be a particularly tight fit, but not loose either.

 

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Put in the bolt release 'sear' and the spring with one hand, and then the pin to keep them in with the other.

 

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Remember to reinstall the valve knocker spring! This is important.

 

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Make sure the screw doesn't pinch it, it will reduce the effectiveness of it and prematurely wear it.

 

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Congrats. You should now have assembled the trigger mech properly if you followed my guide.

Note: if you look where the hammer is, and the sear is, you'll notice they aren't aligned. This will make the sear not catch on the bolt, and the rifle will appear not to work. Don't panic. Tighten the grub screw behind the trigger, there's only one. Tighten it until the hammer is 'underneath' or obstructing the sear. The more it obstructs, the longer your trigger pull. With only the one spring in there like mine, it will be a very light, very short trigger pull. Don't make it too short or it might not catch all the time. Polish your trigger for smoother results.

 

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You should have reassembled your hop + barrel by now, so this is what it should roughly look like, but yours should have the retaining pin in it. The hop will be loose without it.

 

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Reinstall the hop adjuster

 

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Done!

 

Or are you? Nope, still the bolt to do. The mags don't need covering because they're held together with crosshead screws, just undo them. Make sure they're empty first, or you're going to get cold hands.

 

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So you have your bolt, how to disassemble it coming now...

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PART THREE! :D

 

Here is your bolt, but mine has a PCS valve. If yours doesn't have that, don't worry about it and ignore it. It just means my bolt is better than yours ;)

Read the reasons why it makes no difference here in the first post

 

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Turn it over, and take out the two screws that I've already done. There may be a lot of tension behind them, so make sure you're aware of that.

 

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Slide the front off of the bolt, and you'll see a large spring and a flathead screw on top of it.

 

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Undo this small allen grub screw, it'll let you undo the main flathead screw for the big spring.

 

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When you undo this big spring, it will most likely ping a little, be aware of that and make sure you don't loose it. That was an important bit, highlighted in bold ;)

 

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You can slide the bolt handle off, but it has it's own notch, or you could call it a groove, to slide out of/in to.

 

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This valve 'hammer' is one of the most important pieces and will probably wear faster than the rest. Steel upgrades for this and other parts are available, but you'll need to upgrade it all for the steel to be worth it as the steel part will wear other parts out at an increased rate. Still, keep an eye on the condition of this part. This particular one is from a KJW M700, as the stock part in my M40 was completely worn, I may take another picture for reference if I can be bothered ;)

 

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When you get to the stage where you can take the vavle 'hammer' out, you've disassembled the entire bolt pretty much. The nozzle end will almost never need full disassembly, as if it cracks you can pull it out and push a new one on. The PCS valve will screw out if opened far enough, it also has a grub screw similar to the main spring. Remember to put the grub screw you got from the main spring back in or you will suffer a huge loss of power over as little as 3-6 shots, and eventually won't be able to shoot anymore. This is solved by taking the bolt apart again and tightening up the main spring and installing the grub screw, as this stops the main spring from loosening again. Make sure you periodically check the red rubber seal, it won't be red as stock but the G&G rubber pack is red. This can start to show signs of wear from as little as 600-1000 shots, dependant on FPS levels.

 

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Reinstall the bolt

 

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Enjoy your (hopefully) fully functional and cleaned M40!

 

Any questions or grammatical/techical errors in my posts, let me know.

 

Thanks for reading

 

:D

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Nice guide, intuitive and helpful

 

Thanks, didn't take anywhere nearly as long to take the pictures as it did to write up the guide!

 

Now it's just a question of what guns I do next ;)

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I think you have too much free time :P

Good job though

 

Waaay too much free time here.

I think reviews will be in the near future too! If my camera battery didn't die so hard <_<

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Thanks :D

I've seen bits of disassembly guides all over the place, so I was sort of aiming for an all in one, anyone can pick up the rifle and follow this guide sort of thing, and I think I managed it?

 

Definitely more to come though, I actually slightly enjoyed doing this. It wasn't just another task :P

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Thanks :D

I've seen bits of disassembly guides all over the place, so I was sort of aiming for an all in one, anyone can pick up the rifle and follow this guide sort of thing, and I think I managed it?

 

Definitely more to come though, I actually slightly enjoyed doing this. It wasn't just another task :P

Wayy! You got it done then mate :)

Really nice Job, phone died loading but is brilliant, love the rifle as well, where did you get it from and how much was it??:)

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Wayy! You got it done then mate :)

Really nice Job, phone died loading but is brilliant, love the rifle as well, where did you get it from and how much was it??:)

 

I did, and I think it was definitely worth it :D

 

Actually, I got it from this very forum

£126 posted I think it came to in the end. That's right, a whole Tanaka M40 with PCS bolt, KA harris bipod, that strangely nice scope (its got a rangefinder type reticule, I like it!) and a G&G heavy fluted barrel set, pre installed. £126. And I only had to replace two parts, one which I already had :D

 

I think it's safe to say that's my best deal ever :)

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I did, and I think it was definitely worth it :D

 

Actually, I got it from this very forum

£126 posted I think it came to in the end. That's right, a whole Tanaka M40 with PCS bolt, KA harris bipod, that strangely nice scope (its got a rangefinder type reticule, I like it!) and a G&G heavy fluted barrel set, pre installed. £126. And I only had to replace two parts, one which I already had :D

 

I think it's safe to say that's my best deal ever :)

Most definitely :D I just got given an m6 for free though with a 4x32 scope I think :D

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I like the fact that if you search 'Tanaka M40 parts diagram' on google, this thread is the 5ht one down... Not what I was after though.

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