Maruzen M870 Shell-ejector thread

[Grindstone]

Rather than continue to clog up the Shotgun Picture Threat, I figured it would be better to start a thread in the project section. This is a coninuation of the discussion here:

http://www.arniesairsoft.co.uk/forums/index.php?/topic/157637-shotgun-picture-thread/page__view__findpost__p__2500061

 

The aim of this thread is for those who own Maruzen 870/1100 shell-ejecting shotguns to share information regarding the system.

 

As previously discussed between myself and notrabies I sent an email to Redwolf Airsoft requesting information on replacing a broken shell-lifter.

 

A few hours ago, I recieved the following reply:

 

"Yes we can order parts for your gun.

Please look in the manual for you gun and find the exact part number for me.

Then I will request our purchasing department to order it for you.

Unfortunately due to the number of requests for parts, we cannot email

everyone individually when the parts come in. So kindly just check our

website about 2-3 weeks after your request to see if the part has been

uploaded to our site."

 

Unfortunately, I do not have a manual to research the part number and my google-fu does not pull up anything useful.

So is there anyone who has a manual, knows where I can get/view one, or knows the part number?

I appreciate the help.

 

 

 

 

 

 

 

 

Useful Maruzen M870 information

 

Disassembly guide:

http://www.airsoftretreat.com/forums/index.php?topic=81593.0

 

Small upgrade/parts list:

http://www.airsoft-barracks.com/forums/topic/6006-lets-make-a-maruzen-m870-upgrade-list-diys-included/

[hitmanNo2]

I was wondering. Will those G&P AR15 stock sets intended to fit 870s work on M1100s as well? G&P couldn't confirm but I cant see why they wouldn't unless there was a difference in the length of the receiver?

[notrabies]

I was wondering. Will those G&P AR15 stock sets intended to fit 870s work on M1100s as well? G&P couldn't confirm but I cant see why they wouldn't unless there was a difference in the length of the receiver?

If you can find one, almost certainly, all 4 of my stocks are interchangeable between my M870's and M1100's.

[hitmanNo2]

Sweet. Thanks. They still seem to be in stock at a few places unless their stock systems are inaccurate.

[sandstorm]

I have one of those AR stock systems,a nd was unable to fit it into either the M870 or M1100. At least not without dremeling something pretty heavily. The gas hose just comes in from the wrong side of the stock fastening screw.

 

Do you have any pcis on how you fit yours, notrabies?

[notrabies]

I have one of those AR stock systems,a nd was unable to fit it into either the M870 or M1100. At least not without dremeling something pretty heavily. The gas hose just comes in from the wrong side of the stock fastening screw.

 

Do you have any pcis on how you fit yours, notrabies?

Well I don't have any G&P stocks, I have a Maruzen composite stock, a Maruzen wood stock, a Maruzen pistol grip, and a Maruzen pistol grip with an ATI folding stock on it. All 4 of those can be swapped no problem, but it would appear I'm wrong about the G&P then. The gas hose is located above the stock screw on the M870s, and below it on the M1100's, but I never found that to be an issue with the Maruzen stocks, I guess G&P just uses a different system. Could you post some pictures of your AR stock for reference? Maybe we can help figure something out.

 

On one of my stocks, I have to put it on sideways to fit the hose in place, and then I twist the stock into position and tighten the screw, maybe that will work for you.

[sandstorm]

It -should- fit there fine with the 870, but nope. I think the stock is in pieces right now, need to dig it out for photos. ANd I ned to put my shotguns in a pile for some photo-ops anyway...

[Grindstone]

I have either the G&P or KA AR stock adaptor on my 870. I'm not sure which, there are no trademarks or other indications that I can find, but they don't seem to be too dissimilar. I'm at work right now, but when I get home I'll try to snap some shots of it for you.

 

 

Still no luck in finding a part number and no response from RW either.

[Grindstone]

Resurrection!

 

Some bad and good news. Good news; we now know the shell lifter is Part #36. The bad news; no retailer stocks it. The good news; I'm about to send my broken #36 to a fellow with a mill to make a steel replacement piece. When everything is said and done, I'll test it to ensure no issues and pass on his contact info.

As a side note, I'm also sending him my charging arms to replicate in steel. Mine haven't broken yet, but I'd rather have the steel set on hand just in case.

I completely dissected my M870 last night and I'm combing over other potential weak points and so forth. If all goes well with the shell lifter and charging arms, I'll probably send off some more parts for him to make. I'll keep this thread updated with the progress.

 

Additionally, does anyone else have an M4 stock kit on their M870? I don't know which brand mine is, but the screw holding the whole shebang to the receiver doesn't seem to want to stay in solidly. I'm thinking the threads in the receiver are slightly stripped, causing the screw to back out a tad. I'm going to try to pick up a longer screw. If that doesn't work, I'll have another excuse to buy a tap and die set.

[notrabies]

Excellent research!

Another part that would be fantastic to have in steel are the small bits that hold the shells in the tube. They like to warp and deform over time, and while you can fix them with a file, its a major pain to do. Also, since that part is identical in the M870 and M1100, we'd be helping owners of either model at the same time. 3 of my 4 Maruzens would benefit from those to be sure.

 

Here's another question, has anyone found a reliable replacement gas hose yet? I tried using some in my M870 after the last of my Maruzen line started to go, but it was too rigid and wouldn't properly conform to the insides of my pistol grip.

 

Oh and here's something I found out, these shotguns really do not like the cold. They function, but the firepower gets about halved in full stock models below like 50F. I went from slinging shells of 10 in my upgraded M870 to shooting 4.

[Grindstone]

Small update; part recieved, he plans to use hardened steel on the lifter and charging arms

 

Excellent research!

Another part that would be fantastic to have in steel are the small bits that hold the shells in the tube. They like to warp and deform over time, and while you can fix them with a file, its a major pain to do. Also, since that part is identical in the M870 and M1100, we'd be helping owners of either model at the same time. 3 of my 4 Maruzens would benefit from those to be sure.

Do you mean the small tabs on either side of the magazine? I'm sure those would be no problem for him to make (and much easier for me to ship to him! lol).

 

I'm probably going to eventually send him every part there is for him to make out of better metal for a bomb-proof shell-ejecting shotgun

 

Here's another question, has anyone found a reliable replacement gas hose yet? I tried using some in my M870 after the last of my Maruzen line started to go, but it was too rigid and wouldn't properly conform to the insides of my pistol grip.

 

Oh and here's something I found out, these shotguns really do not like the cold. They function, but the firepower gets about halved in full stock models below like 50F. I went from slinging shells of 10 in my upgraded M870 to shooting 4.

When I get the parts back, I plan on taking mine to a local paintball/airsoft shop to get an external rig set up. I'll ask about durable, flexible tubing.

[notrabies]

Just found this the other day:

http://www.palmer-pursuit.com/cart/index.php?main_page=product_info&products_id=823

It uses a 6mm hose, just like the Maruzen does, so all you'd have to do is disconnect your current hose and throw this on, I'll be getting one of these for the M1014 kit Schaap is making anyways, so I'll just get some extra line and another nozzle or two, and all of my shotguns will be setup for it.

[Grindstone]

Basically what I was looking for, but I already have two tanks, I just need the hose, regulator and connector.

Let me know how it works out for you.

[notrabies]

Well here's some good news, they sell the exact same product without the tank: http://palmer-pursuit.com/cart/index.php?main_page=product_info&cPath=75&products_id=822

It only runs up to 200psi, but if I recall correctly that's about the same or a bit higher than green gas on a warm summer day, so it should be just right.

Any word on the custom parts yet?

[Grindstone]

I'm going to see if I can't get something cheaper at a local paintball shop.

 

No word yet. I'll shoot off an email to him tomorrow.

[bankz5152]

Hey,

 

Im thinking about getting one of these again. Though I was reading in the M1014 thread that placing O-Rings over the shells increase its life, power and reliablillty.

 

Where exactly do you place the O-Rings?

 

Also is there anything else worth doing?

[hitmanNo2]

Slide them all the way down the shells so they're sitting tight and flush on the rim. It reduces the wear on the extractor and prevents stove piping from wear.

 

Fitting a piston head for a TM M9 is a good idea as it increases compression. Those are two relatively easy things without messing about trimming or replacing hoses.

[notrabies]

Okay, so the deal is that with a regular M870, no o-rings are needed, the mechanism is light and wear on parts is minimal. Their only issue is low power, but there are work arounds.

The M1100 on the other hand has great power stock, but likes to break itself in one of a few ways.

 

First, the extractor goes, pot metal extractor hitting brass shells means you lose your extractor and stovepipe all day long. What you do to help reduce that is placing an o-ring over the base of each of your shells.

Now the extractor hits rubber which highly reduces (read: it does not eliminate) wear on the parts. The extractor does butcher the o-rings over time, but those are like a $2 for a 10 pack. I forget the actual dimensions, but the out diameter of the o-ring should be slightly smaller than the shell itself to get a snug fit. This makes it annoying to put on the o-rings but its crucial to do so. With o-rigns, my extractor lasted 2-4 months of weekly use and over 1000 shells with ease. New extractors are extremely and almost impossibly rare.

 

Here's what your shell should look like:

and your o-ring should fit inside the circle the perimeter on the top of the shell:

 

 

Next, your shell lifter can snap, replacements are also very rare, but I'm currently testing out Schaap's prototype lifter for the M1014 which should be the best replacement ever. Also, the shell lifter can experience wear that will make your shell lifter load shells incorrectly, causing misfires or shells being ejected without being fired. This is caused by the brass shell bass scraping the guide areas on the top of the lifter.

Prototype part:

 

Original Part:

 

As you can see, Schaap's prototype part is significantly better in design and quality, having two guide lines on the bottom and the arched base allow much better positioning of the shell.

 

Third, your gas line can leak or pop off, simple fix as you just push it back on with some lube/grease, or you can replace the hose. Fairly soon I'll be replacing the hose with some Palmer's air rig hose which should be much better than the Maruzen one. (The shotguns and rig use 6mm hose.)

 

Fourth, your shell retaining blocks can deform over time, mostly caused by the magazine follower hitting them at speed(when you disassemble/reassemble your M1100, slide the lifter in slowly so you don't bang into the blocks) this makes your shells stick in the tube. Luckily, this one is easy to fix as a cheap metal file can be used to reshape the pieces in about 30 seconds, and original replacements are available.

 

So if you get an M870, you focus on increasing its power, and if you get an M1100, you try to keep it working as long as possible. Without any modifications, mine was shooting about 350 with 1 bb on green gas in about 60F weather. The M870s like to shoot about 260-280 on green gas.

[bankz5152]

Thank you very much. That was basically all the information needed!

 

I can see why the Orings would help the problem somewhat.

 

So would the new Schapp lifter stop the stove piping?

 

I used to have both the M1100 & the Revision and loved using them, so much fun! Until they broken and funnily enough I have seen them both circling for the past 5 years with people un able to fix them...

 

Just trying to decide which to buy, an M1100 (would prefer a 870 but they are rare) or a M500 (know them back to front)

[notrabies]

Well you're at a very good time to be wanting to get back into this. Redwolf has 4 M870's and 3 M1100 models instock to choose from. If you order from them they also offer a 400fps upgrade featuring the much desired hammer spring. While its probably not very valuable on an M1100, it makes a massive difference in the power of the M870. Be warned, the full stock is a bit of an issue on M870's because its power output is lower than the discontinued pistol grip versions due to the length of the hose. Also, the hose isn't insulated, so in cold weather my full stock and upgraded M870 performs about the same as my regular shorty M870. An external air rig would theoretically solve this as well. Luckily M870 and M1100 parts are all interchangable, so you could find a pistol grip and gas tank and transform a full stock to a shorty.

 

The lifter would not stop stovepiping, it should help stop jams from improper loading and shell positioning, but not the stovepipiing issue. Him and I have been brainstorming for a while on possible fixes. We're considering an entirely new part, but its pretty complex. If we make the extractor out of aluminum or another tough metal, it will eat through o-rings and will destroy the brass shell bases, making the whole change worthless. However, we're working on a variety of solutions that will work in tandem with a toughened extractor, probably a rubber buffer in between the shell and the extractor that will do the same thing as the o-rings. If our plans succeed it'll be a cheap and easy to replace part, but it will be mounted on the door itself so you'll only need one at a time, instead of one for every shell you own.

 

The M500 will probably be better, but I always hear bad things about them developing unfixable leaks over time. Schaap and I are dedicated to making the M1100's invincible, so we'll keep working on parts until they're perfect.

[bankz5152]

Fantastic, its good to see airsofters working on guns improving them past the manufacturers.

 

It sounds good, like it would work, and work well.

 

The M500s can develop leaks but they are 'fixable' well not permenantly but can make it slow enough that it will last 8 hours or so. Its all about the utter idiocy of the design. The hammer sits on the release valve.. and it eats orings lol.

 

Ill keep check back on this!

 

Thanks again.

[Horsem4n]

with the m500s the leaks are never unfixable but they happen pretty often.

 

been wanting to get an m1100 for a while. i have seen a mod for the extractor done by wonkothesane where he drills a hole in the bolt and sticks a machine screw in there and shapes the screw to work as the extractor. i can see that you would dissaproove as its a thougher material than the brass on the shells, but its a viable replacement method. however, it may not matter. i have an idea for a cheap way to make disposable shells that are one time use or a couple time use...

 

do the m1100s have a bolt catch function? i have seen some that do and others that dont, so i would just like some clarification.

[bankz5152]

Whats this disposable shell idea? Go on.

[Horsem4n]

Well, I havnt seen one up close yet, but from what I can see, its just a shell shaped tube that harbors bbs with o'rings at either end. So, I figured you can make a rubber mold of a shell, fill it with a material that when solid, will be extractable. Then, it will be drilled and o'rings will be glued at both ends to hold bbs. It's pretty simple, just takes some model making knowhow and a drill press.

[notrabies]

Well I've tried contacting wonko once or twice with no results, I was gonna try to buy one of his custom made ones as I don't have the tools myself.

I like the disposable shell idea for a number of reasons, mainly because the o-ring type items that hold bb's in place wear down pretty quick, which results in shells loosing bb's all over the place due to the violence of the M1100's mechanism. I reserver my worn down shells for my M870's, as the pump action is much slower and doesn't really affect the old shells. Not having to pick up shells and having them be cheap is great, I'd probably get some for outdoor skirmishing use.

In other exciting news, I did manage to fit and work out Schaap's custom lifter. My M1100 has seen about 10x the life of the average one since I've taken extreme care with my extractor, so it took a significant amount of lithium grease and some minor filing of parts to get everything smooth. Schaap's part is actually easier to install than the original lifter. Overall is was about 2 days of work and a dozen disassemblies.

Here's a video of it in action for those who aren't tuned into the M1014 thread:

http://www.youtube.com/watch?v=YLK0s60yP48&feature=plcp&context=C334b245UDOEgsToPDskIW6DvZCSY3_JVNV-n8MT7Q