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spetsnazdave87

Tokyo Marui M870 Tactical Gas Tri-shot Shotgun- picture, text and video review

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You could definitely make one yourself, if you were willing to do the modifications necessary. You would need to hollow out a RS M870 stock and adapt it for a thinner gas tank - maybe an adapted 20rd STANAG or something similar - or fit a permanently attached one that could be glued into place to support the wood. You could do the same with the plastic MagPul furniture everyone's been pining after, but it would be a lot of work.

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Mmmm the diameter of the handguard is the same as the Tanaka ones (29 mm), so thanks to the Spam info and other photos I think that maybe its plausible to fit the Marui flashlight on mines without mod, or with a small one. The opposite, a Tanaka or RS handguard on the Marui, will need mod.

 

Just hope it would not be very expensive since the RS is about 200€.

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Still in two minds about the magpul fore-end. I love the look, but not sure if I even have the skills to modify it to fit! 

 

I don't suppose anyone who's already done it would be willing to write up a guide, including whatever takedown of the 870 is required?  

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Still in two minds about the magpul fore-end. I love the look, but not sure if I even have the skills to modify it to fit! 

 

I don't suppose anyone who's already done it would be willing to write up a guide, including whatever takedown of the 870 is required?  

One of the lads has provided pretty good instructions in response to my query for how to do it...back a couple of pages, but definitely makes sense. I'm in the same boat as you though...want the look, not sure if I have the patience/skill :D

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One of the lads has provided pretty good instructions in response to my query for how to do it...back a couple of pages, but definitely makes sense. I'm in the same boat as you though...want the look, not sure if I have the patience/skill :D

 

Haha I hear ya! Was hoping for a video, I learnt a bit off YouTube for the easier stuff like changing hops and barrels - but when it comes to stuff that needs chopping, it's always best to watch someone do it first! :D Learning with the eyes and all that... not to mention the take down, very clueless there! :)

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Haha I hear ya! Was hoping for a video, I learnt a bit off YouTube for the easier stuff like changing hops and barrels - but when it comes to stuff that needs chopping, it's always best to watch someone do it first! :D Learning with the eyes and all that... not to mention the take down, very clueless there! :)

could you share links for the "how to's."

 

I've only seen video reviews. I had to assemble mine when I first got it but am dredding when I get a new pump handle or god forbid any internal servicing haha

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could you share links for the "how to's."

 

I've only seen video reviews. I had to assemble mine when I first got it but am dredding when I get a new pump handle or god forbid any internal servicing haha

 

Sorry friend, but I'm looking for videos myself! :) I've nothing to share.

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I've never tried to mess with my guns. I prefer just paying the site to do it. It may cost more but at least I know its being done by someone who knows what he's doing and its their job

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Except when they take too damn long and can't give a straight answer! Sadly, a story I am living right now! A record 5 months so far...!

 

Looking at the attachment for the shell carrier, I think it's a matter of some hex bolts and pins -- THAT I'm sure I can manage. Maybe even the mag tube extension as it looks like it's a twist thing? The one that worries me at the moment is the fore end / pump grip as those parts are probably sprung and who knows what other horrors await the novice engineer?? :s

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THe mag-extension is very easy, you just screw off the original cap at the end of your magazine tube and just screw on the bit.

 

simple.

 

but yeah, my experience with taking apart my maruzen and the ACM 500 is that you have to take the stock off then take out the internal, to get arms of the foregrip to come off, before you can even think about getting it off the magazine tube.

 

For reference, im looking at dismantling guides of the original spring powered TM shotguns, as this is what the m870 is based upon. 

 

I'll get back to you if i feel confidence enough to start and get documenting it. :)

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THe mag-extension is very easy, you just screw off the original cap at the end of your magazine tube and just screw on the bit.

 

simple.

 

but yeah, my experience with taking apart my maruzen and the ACM 500 is that you have to take the stock off then take out the internal, to get arms of the foregrip to come off, before you can even think about getting it off the magazine tube.

 

For reference, im looking at dismantling guides of the original spring powered TM shotguns, as this is what the m870 is based upon. 

 

I'll get back to you if i feel confidence enough to start and get documenting it. :)

This(TM M3) here is pretty descriptive and has a lot of pictures.

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Me too! but thanks for the concern.  :D

 

Right now, i've decided to take a break, still can't get to my original goal of getting to that forearm.A very tricky issue has come up.  My G&P replacement will have to wait until tomorrow.

If my theory is correct, seems like i need to get a new tool to get down that long barrel...

Anyway, i hope i get it done tomorrow! i documented everything so far, but it seems like im still missing a spring...or something that suspiciously looks like it should have a spring in it. But i can't for the life of me find it, remember seeing it or see it in any of my photo, how strange, but seems like it doesn't need it(?) oh well, fingers crossed that im correct, or it's back to square one again.  :rolleyes:

 

 

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DSC_0279.JPG

 

hmmm.....60% there! But how do i get the outer barrel and the forearm off? So troublesome..... 

 

Get a tub for all your screws and make sure you don't lose the springs from the right hand side - there's about 4 of them that will pop off at a moments notice.  One of the spring loaded bits is a small silver lever with slot in it - i recommend taking the sliding follower which sits in the slot out too to keep it safe.

 

To get the forearm off you need to remove the front bracket that connects the shell tube to the barrel - there is a screw hole in the underside that goes right the way through the shell tube.  This screw goes into a small removeable rectangular nut on the inside of the barrel, make sure you don't lose that either as it just slides out (Pro-tip: when screwing this back in, grab a marker pen like a thick sharpie or something similar that will fit inside the outer barrel - slide the rectangular nut back into place and then drop the pen/whatever down the barrel to hold it in place while you put the screw back in).

Once you have the front bracket off (It's very tight, I tend to lever the gap between the barrel and shell tube wider with a screwdriver to get it off and on), you can slide off the forearm gently - the side arms will catch in a few places, just pry them off of anything it catches on, don't try and force it. 

 

To remove the shell tube and outer barrel, there are screws on the underside of the shell tube that are hidden by the forearm - unscrew these and the shell tube slides off, which exposes the screws holding the outer barrel on.

 

I should make a video...

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Found a buttstock/shell carrier solution for those that are having that issue with their butt pad falling off:
http://www.evike.com/products/45245

 

Also, I was going to write something up on how to get your fore end off, but didn't get around to it yesterday.  I don't have any pictures, so my instructions are going to be without, if you have pictures and you want to send them to me I'll put everything together and get a tutorial up.  I'm also going to be going from memory, so I'm hoping i can get it all right.  If someone wants to scan their manual and send it to me I'll upload it somewhere I'll revise this write up with part numbers.

 

 

 

Basically, the major steps are:
1. remove buttstock
2. remove body covering
3. dismantle barrel assembly
4. remove fore end
...
99. Re-assembly

 

Some reference points and notes before we start:
* left and right sides of the shotgun will be determined as the shooter's left and right side as if he were standing behind the gun.  ie, the right side of the gun is where the shell ejection/round selector is.
* start with the gun uncocked.
* don't force anything, the gun has been very well designed, so that the pieces really do just fall into place, except one part (that I've found).

 

 

 

 

1.  REMOVE BUTTSTOCK

Fairly straight forward, take the buttpad off, and use a screw driver to remove the one screw holding it to the body.  Take note not to lose the o-rings between the body and buttstock.

 

You should now have the buttstock off and you will have 2 pieces that will be loose from the gun:
- rubber butt pad
- long screw

 

 

 

 

 

2.  REMOVE BODY COVERING

Tap the two body pins out from the body.  They are knurled to one side so tap them out from the left side and let them fall out from the right side.

 

Remove the trigger assembly by pulling down on the trigger guard and the assembly will come down and out, you may need to wiggle it from front to back to get it out (mine was caught on something but it came out with some wiggling).

 

With the trigger assembly out and the shell door closed you can slide the body off to the rear, there are no other screws holding this in place. While you are doing this there are 2 areas you will need to watch for on the right side of the body.

 

As the body goes back you will see 1 small spring in a long thin silver plate, careful not to snag this spring and plate, at the end of the spring is a small metal piece that runs in the channel behind this plate, careful not to lose that piece.  As the body passes this there's another small spring that sits in a channel to the rear of the ejection port covering (you might actually see this spring through the ejection port on the body as the body goes back).

 

You should now have the body off and you will have 7 pieces that will be loose from the gun:
- 2x body pins
- 2x small springs
- Ejection port covering
- small metal piece that sits in the channel with the long thin silver plate
- trigger assembly

 

 

 

 

 

3. DISMANTLE BARREL ASSEMBLY

Remove the shell tube cap.

 

Remove the screw between the shell tube and the barrel.  You will find a small hole in the ring that sits between the shell tube cap and the fore end.  Use a small philips screw driver to remove the screw, take care not to strip this screw head.  Once this screw is removed you will have another part come loose from inside the barrel, a small silver rectangular piece, slide the piece out from the barrel.  Take note on the orientation of this piece, it should be rounded corners to the rear of the gun.

 

This next part is the only part I found where I had to "force" the part out (I may have been doing it wrong but I couldn't find/think of getting this part out any other way).  Pull the barrel and shell tube away from each other so you can take that ring off sitting on the end of the shell tube.

 

You should now have the ring off and you will have 4 pieces that will be loose from the gun:
- ring that attaches between shell tube and barrel
- button head screw
- silver piece that goes in the barrel
- shell tube cap

 

 

 

 

 

4. REMOVE FORE END

Final stretch.  Take the cocking arms from the rear and pull them away from the body assembly at the rear.  Slide the fore end towards the front while you have the cocking arms pulled apart to clear the body and its attaching points.

 

You should now have the fore end off.

 

If you want to remove the fore grip off take the retaining nut off the front of the fore end with some pliers using the notches in the retaining nut (if you got a Magpul MOE fore end it will include a convenient tool for removing the retaining nut).  The fore grip will slide off the grip tube.

 

 

 

 

...

 

 

 

 

So that's how you take the fore end off the shot gun, if you want to take it further to remove the barrel here's the gist of that:
- remove flush head screw from bottom of shell tube
- remove shell tube by sliding it forward and off
- remove 2 long screws found underneath shell tube
- remove 2 small flush head screws from either side at rear of barrel

 

The rest of the outer barrel assembly will now come away from the body revealing the hop units and inner barrels.  Note, the barrel spacer may have come off with the outer barrel, and that will need to be placed back on the inner barrels before placing the outer barrel at re-assembly.

 

 

 

 

 

99.  RE-ASSEMBLY

Put it all back together reversing the steps.  Here are some things to take note of during reassembly:

 

There's one part that's bound to give everyone grief.  It's that small rectangular silver piece that goes in the barrel that needs to be have a screw put through it.  I found that the BB tube loader was just the right length and the right width to hold that silver piece in place while you tried to put a screw in it.  What a PITA though.

 

Put the fore end and cocking arms back in place and try to carefully rack the assembly to make sure it's all lined up and everything is in place (just make sure it moves freely and everything is engaging as it should).

 

Take note of the springs when sliding the body back on, you will probably have to hold that spring in place that sits in the thin silver plate so it doesn't pop out.  The spring to the rear of the ejector plate won't be under much tension when you place the body back on.

 

When placing the trigger assembly back in place, make sure the shell door release is in the closed position in the trigger assembly, or it won't go into the body assembly correctly.

 

 

 

 

 

 

 

END

 

And I think that about does it.  If you have any problems, feel free to ask, or if you get stuck, take a picture and post it and I'll try to help you out.

Edited by p.phresh
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