Maruzen M870 EB Custom

Stock Specifications Model Remington m870 ABS stock FPS unknown at this time Length: ~900mm Weight: ~2,400g Ammo capacity: 4 + 1 shells 3-10 bb's per shell

"A homage to possibly the most fun airsoft gun, I have ever used."
or
"oh-so macho, but rather impractical..."

Options 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. Well 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) Well 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. It was then that I got a call from Edgar Brothers. Mike (Police and Military Sales) was very interested in having a look at the Maruzen 870 to see what they could do. The 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! All of the parts, although supplied by Edgar Brothers, are available through AirsoftArmoury.

For 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.

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

The following parts will not fit:

In 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.

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

SureFire Light/Laser Mounting: You may remember many moons ago me mentioning the shell extension tube for the M870 (such as the one from Advanced Technology), 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.

The 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 Uss).

Scope mount: 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.

One 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.

The 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.

For 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

Red Dot scope: The RedDot fitted is an EdgarBrother's Opti-Mate 90 (1x30 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 allen-keys.

Stock and grip: The stock is an Advanced Technology 12GA Top Folding Stock with Pistol Grip "...One 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..." Advanced Technology website One 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 really. To 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. To 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. As 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. On 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 website.

CO2 rig: 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:

Vertical 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.

The 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.

Not 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.

The 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 02).

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