Home Reviews M870 Remington M870 custom parts

Remington M870 custom parts

by Arnie

M870 EB Custom

Model Remington
m870 ABS stock
at this time
Length: ~900mm
Weight: ~2,400g


+ 1 shells

bb’s per shell

homage to possibly the most fun airsoft gun, I have ever used.”
macho, but rather impractical…”

additions and modifications:
Okeydoke, so it’s
somewhat acclaimed that the Maruzen 870 has some downsides.
It’s very realistic and very functional, but there are two
problems. One is that it really stinks in terms of the little
‘pop’ that it makes when you pull the trigger. The other issue
is that the power is rather pathetic.

the first issue was fairly easy to solve, strip away the full
stock and replace the tank with 3PSA/SMK
CO2 powerlet adapter
. (see
previous article for more notes)

I got to this point and then got rather stumped and put the
870 back into the toy cupboard whilst I pondered what to do.

was then that I got a call from Edgar
. Mike (Police and Military Sales) was very interested
in having a look at the Maruzen 870 to see what they could

following article is the documentation of the work that he
has done, and the real-steel parts that you can and can’t
fit to a Maruzen M870. By all accounts they had a lot of fun
doing the work too!

of the parts, although supplied by Edgar
, are available through AirsoftArmoury.

anyone that is a little confused, Edgar Brothers will not
deal directly with the public, and will instead refer you to their
authorized Airsoft dealer (AirsoftArmoury).
If you are a dealership or retailer interested in contacting Edgar
Brothers you can contact them on 01625 613177, or fax 01625 615276.

what fits?
In general most real steel parts do not fit flush
with the M870’s body, happily though these parts did fit rather

  • Advanced
    Technology folding stock
  • Millett
    side saddle mount (Did not fit perfectly as it only went through
    one hole but it’s still secure though)
  • EB OPTI-90
    Red dot sight
  • Sure-Fire
    tactical light – alternative system as dedicated fore end 618
    did not fit.

following parts will not fit:

  • Pachmayr
    Magazine extender
  • Sure-Fire
    618 tac light
  • B-Square
    side saddle mount
  • Pachmayr
    heat shield. – will not fit with the present Sure-Fire mount.

conclusion really, Maruzen’s M870 copy is somewhat out in quite
a few dimensions, specifically the two retaining pins in the receiver
that are removed and replaced to fit scope mounts (and other add-ons)
are too close together. This isn’t great news for anyone looking
for a mount to put on their Maruzen M870.

enough of the bad news, lets get on to what does and doesn’t fit.

Light/Laser Mounting
: You may remember many moons
ago me mentioning the shell extension tube for the M870 (such
as the one from Advanced
), well sadly you can forget it, as the real
steel version won’t fit the Maruzen.

Also of
note is that the Maruzen shells are actually smaller than
real 12 gauge shells, so you’ll find that plastic shell holders
(such as stock or side mounted paddles) won’t quite work without
modification. The shell extension from an old shell fed Maruzen
M1100 should fit, but I’ve yet to try that myself.

other item that I mentioned (again this was quite some time
ago) was the SureFire grip for the M870, sadly this won’t
fit either.

By all
accounts the real tactical grips are not even a close fit,
so sadly you’ll have to forget all real steel replacement
grips for the Maruzen M870. This is incredibly sad as there
are some truly gorgeous grips out there for the M870 by

Okay.. so the news isn’t great so far, but it
brightens up from here on in (oh darn that’s a really
bad joke).

SureFire under-barrel clamp (M19) does fit however
(as seen to the left), so all is not lost. Fitted
to this is a SureFire lamp, and a standard momentary
on pressure operated tail cap switch.

sticky velcro glue isn’t particularly good for sticking
to this grip surface, so you’ll need to wipe the glue
off the pad (an alcohol swab will do), and then stick
the velcro strip to the grip with some superglue.
You can find the manual for the M19 mount (PDF format)
located on this
website here

light fitted is a SureFire Model 650 Universal Tactical Light. This
is the 6 volt version that takes two DL134a batteries. The tail
end cap has been replaced with a Universal Housing/Switch.(model

As mentioned before a lot of the specifications for the
Maruzen M870 are close to the real steel but not quite the same.
With the receiver pins being slightly out of place it’s difficult
to get a mount that fits properly.

that does fit securely is the Millet 870/1100 shotgun saddle mount.
The mount fits by being secured with two replacement receiver pins.
The Maruzen pins are merely kept in by friction. These pins are
poked out and replaced by the Millet versions, which are basically
bolts. You place the mount over the receiver and then put the bolt
through the receiver bolt hole.

bad news is that you’ll only be able to get one of the pins to fit,
as the distance between the two pin holes is different from the
real thing. The good news is that even with one pin in the saddle
mount is incredibly secure.

future reference anyone looking to make a keymaster with the M870
can easily use this mount to mate a RIS rail on a foregrip with
the scope rail on the top of this new saddle mount

Dot scope:
The RedDot fitted is an EdgarBrother’s Opti-Mate
90 (1×30 4MOA). The reddot is EB’s own brand, but that’s not to
say that it’s anything plain. In the box you’ll find scope extensions,
a filter end cap, ring mounts, lense covers and a collection of

and grip
: The stock is an Advanced Technology 12GA Top
Folding Stock with Pistol Grip

of 11 components in the Interchangeable Shotgun System. The
ultimate compact, tough design. Shotgun functions in open
or closed position. Includes rear pistol grip. Quick release
button allows buttstock to fold/unfold instantly. Sling swivel
stud included and is reversible for right or left-handed shooters.
Does NOT include shell holder. Made in USA of black, glass-filled
nylon. Mfg Lifetime Warranty…”
Technology website

of the handy things about this stock is that it comes with
a selection of spacers (and bolts) that allows it to fit to
the Mossberg 500/590, Remington 870, Winchester 1200/1300,
Maverick 88 and Norinco 98 Series.. which is just about anything

close the stock you press the the quick-release button (located
on the left side of the grip), while lifting the stock upward.
As the arm closes down on the barrel, the butt plate will
fold flat. The quick-release button will snap out securely
locking the stock in the closed position.

open the stock you need to press the quick-release button
while lifting the stock away from the barrel. When the stock
is fully open, the button will lock into position.

the stock folds flush with the shotty frame you will need to
file down the catch area to ensure a secure locking position
(see inset image). The bolts that come with the stock may not
fit the 870 (or another shotgun, if you choose to use this stock
on something else) So you may have to locate another suitable
bolt for fitment.

the M870 there’s just enough space to pass the gas hose through
the new pistol grip near where the securing bolt is. It’s
a good idea to use some form of loctite on the bolts, as things
do have a habit of undoing themselves. You can find complete
installation instructions at the ATi

I’m somewhat undecided as to where to locate the gas rig
at the moment at the moment I’ve chopped 4 inches of spare hose
off, and clipped the gas tank to the underside of the stock It’s
actually easier than you think, as with a little pressure the CO2
adapter’s belt clip fits through the holes in the underside of the
ATi stock. You can see the replacement parts here:

grips (pistolgrip / foregrip) on a shotgun are rather weird to use,
and having a read around a lot of the experts around the world can’t
make their mind up about them. I consider the folding stock and
pistol grip here to be a great improvement. You will notice that
getting to the cocking release lever in front of the grip is somewhat
more awkward compared to when the normal solid stock is fitted.

only one problem with the folding stock is that you can’t fold the
stock over with the gas line attached in it’s present form. This is
simply because Maruzen’s gas hose is far too inflexible – it’s not
the fault of the stock. In one of those mythical free moments that
I occasionally get the 870 is going to be stripped and have the hose
replaced with a better quality version. The hose will be clipped to
just poke out behind the grip and will have a quick release gas nozzle
fitted to it. That way the CO2 power rig can simply be quickly and
easily clipped to it via normal BV coiled hose system sold with the
CO2 adapter.

only will that mean that the gas adapter can be detached for use
on other gear if needed, but the gas hose (being coiled) will then
allow the easy folding and opening of the stock.

combat shotgun:
So why fit a lamp to a shotgun? The favored
weapon of a point man (in real life) is the shotgun, and the fitment
of a Surefire allows simple target identification and the “non-lethal
force option of white light”
(SureFire CombatTactics Nov

of the nature of a shotgun and the roles they are used in (close
range) a lamp is essential.

  • A simple enough reason for the use of a lamp, even in what we might
    consider daylight, is that a good quality lamp allows simple identification
    and location of a target and the equipment they may or may not be
    carrying. In short, you could distinguish a pen from a pistol.

  • The blinding effect of a lamp can be used to the operators advantage,
    it can blind a potential attacker, and at close range used effectively
    can place them off balance.

Whilst the real life
use and tactics of lamps may not entirely apply to the world of Airsoft,
the theory and functionality are still sound.

A bright light in
someone’s face causes an involuntary reaction (much like a deer in a car’s
headlamp beam) that is hard to fight, and in a tense scenario may give
you the extra second you need to make the correct decision.

been having a read of SureFire CombatTactics Nov 02 and looking
into the work that SureFire put into their products. As Allen (aka
DumboRAT) always says there’s a lot more to lamps and torches than
just how bright they are – in fact I could start an entire website
about them( I would if I had the time and I got paid to do it full-time

take a lot of feedback on their products and improve them based
on these comments. The improvements range from such minor (yet important)
improvements such as the battery packs. For example (according to
SureFire) battery packs take more of a pounding when fitted to a
shotgun than any other firearm.

this in mind SureFire make special battery packs that can withstand
the recoil of a 12 gauge shot. The packs feature special buffers
between the battery cells (packs are available in 6 and 9 volt versions).
True this doesn’t really affect Airsoft equipment, but there’s so
much attention to detail it really is worth mentioning.

Well out the box the Maruzen M870 really is a great replica
to play with but it’s not at all functional as a tactical
Airsoft piece, anyone that says different really is fibbing
to you. The racking of the pump sounds very nice, and the
functionality is there, but the measly ‘pop’ issued when firing
it is really laughable.

until you rig the 870 up with the CO2 adapter – the extra
‘oomph’ and increased retort is very pleasing. That said you
should beware, Maruzen never intended this item for use with
CO2, in fact they designed it for use with 0.12g BBs and 134a.
In fitting the CO2 I have taken this piece above and beyond
it’s intended specifications. How long will it survive before
something in the Maruzen gas system fails? Who knows.. I just
know that it’ll be fun using the M870 until it does eventually
fail. When that time comes I’ll simply buy one of the newer
versions out there and swap the guts and parts over.

don’t blame me if you try the CO2 rig at home and blow your
own M870 to pieces – I have warned you. No honest – I really

to the very kind folks at Edgar
specifically Mike Newman we know know what parts
will fit, and those that fit after a small modification here
and there. Now thanks to AirsoftArmoury
you can order through them any of the parts I have mentioned

on this article in the forums

CO2 powerlet adapter review
Review #1
M870 review #2
M870 review #3
M870 custom parts review


– the makers of the mount and lamp fitted here



:M870 review -the only English review I could find
M870 Riot version review
– a review in Japanese

Guns in Russia”
M870 review – a review in Russian

Interesting links:
M870 Manual
– The official manual for the real-steel
Remington Pump action
Tac Mount
– A Page with details of kits to mount Surefire
lights and lasers onto the shotgun
Extension Kit
@ ATI Gun Stocks – details of magasine
extension tubes for the M870/M1100
– the official US Government’s operators guide
to the M870
Remington 870 laser mounting
– a custom
method for fitting a laser unit to the end of the 870, not a method
I would recommend though.
Tactical Shotgun
” – an article about shotguns and
their use in a tactical environment. It’s a VERY good read The original
website is from this page here: http://www.angelfire.com/tx/ShotGun/
“The MultiPurpose Shotgun”

page last updated:
Thursday, February 20, 2003 7:19 PM

Copyright 2003Arnie’s


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