Problem Solving Guide For The Maruzen M1100 Shotgun

Discuss your favorite Airsoft weaponry.

Moderators: THE ARCHANGEL, Guges Mk3

Post Reply
User avatar
Jin
Posting King
Posts: 2022
Joined: Sat Apr 15, 2006 12:24 pm
Location: Saint Paul, MN
Contact:

Problem Solving Guide For The Maruzen M1100 Shotgun

Post by Jin » Tue Jun 30, 2009 3:14 pm

Every now and then I like writing articles about airsoft guns I like, particularly more uncommon guns like sniper rifles, shotguns, and gas blowback pistols and SMGs. So, for my newest article here's a little guide that should be helpful to Maruzen M1100 owners.

Over the past few years I've owned a couple, and worked on several more, Maruzen M1100s.
They're fun guns to play around with and reasonably effective in indoor CQB situations, but they do have their fair share of issues. Fortunately I've learned a few little known tricks over the years for overcoming some of their reliability issues and I thought it might be worth sharing to help out those who might enjoy using a M1100 but are having trouble with their guns.

So here's a few tips and tricks for getting the most out of your M1100...




(1) Fixing Ejection Problems (I.E. Stovepiping)
===========================================

The most common issue Maruzen M1100s seem to experience after a bit of use is stovepiping of the shells, which where the shell jams between the bolt and receiver rather than ejecting properly after firing. This most often occurs after a short time using green gas or propane but it will happen on 134a and duster gas as well after enough use.
The easiest way to deal with this problem is to nip it in the bud before it starts happening, but if it is already happening to you there is an easy way to fix it. But before we get to the fix, I feel it's important to understand why this problem is happening.

What is going on here is that on the inside of the bolt there is a little triangular shaped outcropping known as the "extractor". After the gun fires the bolt flies backwards and the extractor hits the brass lip at the base of the shell and the angle and force of this impact on the shell's brass lip ejects it out of the receiver. Now the reason the M1100 often stovepipes shells instead of ejecting them properly is because over time that little extractor on the inside of the bolt warps and/or wears down and no longer hits the brass base of the shell at the angle it should. Why does this happen?
Well, the base of the shells are made out of a very tough brass and the extractor is made out of a soft pot metal. And if you smack a piece of soft potmetal into a piece of hard brass over and over eventually that soft pot metal will either wear down or bend out of shape, and this is what is happening to the extractor every time you fire the gun. Eventually the extractor wears down and/or bends out of shape and can no longer eject shells properly. This happens faster on green gas or propane since the impact of the extractor on the shell's brass lip is much harder than on the lower powered 134a or duster gases, but it will happen eventually even on the lower powered gasses.

And now for the fix... the easiest way to fix this problem is to give the extractor something much softer to impact against then the hard brass lip of the shells. To do this just get an o-ring that is just big enough to slide onto the shell from the front and fit over the brass base of the shell with a little stretching. Slide the o-ring all the way down the shell until it is sitting flush against the brass lip at the base of the shell, you want this o-ring to be good and snug so it won't slip out of place.
Now when your gun fires the soft pot metal extractor will hit the rubber o-ring rather than the hard brass lip at the base of the shell, which will allow the shells to be ejected properly on any gas without causing any wear and tear on the extractor since the rubber o-ring is much softer than the extractor.
I highly recommend you put 1 o-ring on each of your shells before ever firing your M1100 to insure a long reliable lifespan for your extractor, but if your gun is already having stovepiping problems this will fix the problem in most cases.

Another reason the Maruzen M1100 can stovepipe shells is when running on green gas or propane the bolt moves a bit faster than on the lower powered gasses. Because of this the shell often does not have time to fully eject before the bolt slams forward again and this can result in a stovepipe with the shell jammed between the receiver and the bolt. Fortunately, putting an o-ring infront of the brass lip on the shells should fix this too! The o-ring sits a few millimeters farther forward than the brass lip the extractor would normally catch on which causes the shell to be ejected a fraction of a second sooner than it normally would. Because the shell is being ejected a little sooner than it normally would it gives the shell a little more time to be ejected before the bolt slams forward again, allowing the gun to now cycle more reliably on green gas or propane. If you try this fix and your shells still stovepipe often I suggest stacking a second o-ring on the base of the shell which will cause the shell to be ejected a little sooner and should clear up your ejection problems.


In the overwhelming majority of cases putting an o-ring on each shell will fix any ejection problems your gun may have. However, with M1100s that have been used for a very long time on green gas without putting any o-rings around the shell bases it is possible for the extractor to warp or wear down to the point that no amount of o-rings will allow the shells to eject properly. In this case, what you can do (if you have the tools and skill to do it) is to make a new extractor out of brass.
To do this, cut out the entire extractor from the bolt which will leave a hollow rectangular hole in the bolt. Then, take a small sheet of hard brass and cut it to the approximate size of the original extractor and bend it to make a new extractor, drill and tap a M4 sized hole on the outside of the bolt just behind the rectangular extractor hollow, and secure the new brass extractor to the outside of the bolt with a M4 screw. I'm sure this sounds very confusing but when it's complete it should look something like the picture below...

Image

The bolt on top is the original, the one below is the bolt with the new home made extractor.

As I said, in the overwhelming majority of cases the simple addition of a o-ring or two to the base of the shells will fix any ejection problems. But if your extractor is totally shot and no amount of o-rings will fix the ejection problem it is possible to make a new one with the right tools and skills.







(2) Boost That Power!
=====================

While the Maruzen M1100 series does have substantially more power than the pump action M870 shell ejecting series it is still fairly weak compared to most guns you'll see on the field. You can however get a small power increase that will add a little extra range to your shots with a very simple modification. First, remove the gas tank from the buttstock of the gun. Now, unscrew the long phillips head screw inside the plastic hollow in the stock that the gas tank sits in. You can now slide out the plastic hollow that the gas tank sits in and you will notice a brass nozzle with a hose connected to it sitting in the base of the hollow. This brass nozzle is held in place in the plastic hollow by a small metal pin, slide out the pin and you can remove the plastic hollow for the gas tank from the nozzle and then slide off the entire stock.

Once you do this you'll notice the hose with the brass nozzle that connects to the gas tank is extremely long and probably kinked up in a few places. A simple way to boost your power is to trim this hose to the minimum length necessary to reach the end of the stock and then reinstall the brass nozzle on the end of the hose, reassemble the stock, gas tank hollow, and gas tank. By shortening this hose you should see a small power and range increase.

Also, if you are using green gas or propane (which you probably are for decent range) from time to time it is possible for this gas hose to blow itself completely off the brass nozzle that connects to the gas tank or the other end which connects to the gun's internal mech. This is because the hose isn't rated for the pressure of green gas (roughly 95 to 110 PSI depending on temperature) and this problem can be easily fixed by replacing the hose with a stronger hose of the same size from the hardware store, auto parts store, or pet supply store (in the fish section) that is rated for the pressure you will be putting on it. Another advantage of upgrading to a stronger hose is that it will be less likely to bend and kink up, which will give you a small power boost as well.







(3) Replacing the Piston Head & Improving Compression
=================================================

After enough use on propane or green gas the Maruzen M1100's piston head will likely rip or deform in such a way that your power drops substantially may occasionally not cycle correctly. Maruzen does not offer replacement piston heads anywhere outside of Japan, but fortunately for you a Tokyo Marui M9 piston head or any aftermarket piston head made to fit the Tokyo Marui M9 is a perfect drop in replacement for the original M1100 piston head. It will also improve compression slightly which will give you a very small power boost.

If you are having trouble disassembling your M1100 to get to the piston head please see THIS guide on the M1100 disassembly.







(4) Fixing a Sticky Trigger
========================

An occasional problem with the M1100 series is that the trigger will stick and jam up when you try to pull it. This doesn't happen often, but when it does happen it can be a real pain the buttocks to get unstuck. This jamming is caused by a small spring with a ball bearing on each end that sits inside the trigger assembly and allows the trigger to "click" into the forward and backward positions. Occasionally it likes to stick and not allow you to pull the trigger. Unfortunately I don't have any pictures of this spring or it's position in the trigger, but if you follow THIS guide on the M1100 disassembly you will easily find the spring in the trigger assembly with a ball bearing on each end once you get down to the trigger mechanism of the gun.

So, in order to prevent the trigger jamming up I highly recommend removing this spring and the ball bearings on each end. Once you remove the spring and bearings you will have a much lighter trigger pull and you will never have to worry about trigger jamming again. The downside of removing this spring is that you will now have to pull the trigger quickly and sharply when you fire the gun. If pull the trigger slowly and gently after this spring is removed there's a good chance the gas release valve in the gun's internal mech will not fully open when the trigger is pulled which will result in a very weakly powered shot and a stovepipe upon ejection. So, if you remove this spring and bearing assembly make sure that you always pull the trigger quickly and decisively when you fire the gun.







(5) Curing Magazine Tube Feeding Problems
========================================

After a long enough period of regular use it is possible that you may experience problems with shells not feeding properly from the magazine tube onto the shell loading door that lifts the shell up to the bolt. If you cycle the gun and no shell feeds from the magazine tube onto the shell loading door it's possible that the two latches that hold the shells inside the magazine tube may have warped or deformed slightly over time, causing them to not release a shell from the magazine tube when they should.

To fix this, follow THIS guide on the M1100 disassembly up to step 8. At that point you can remove the two magazine tube latches and examine them for any deformities. While replacements for these latches are not available from Maruzen any feeding problems associated with these latches can usually be easily fixed by ever so slightly filing down the inward most lip of the latch that contacts the brass base of the shells. Often these latches will warp and elongate a bit over time, so filing them down to be just a half a millimeter or so shorter will usually clear up any problems with the shells feeding from the magazine tube onto the shell loading door.







(6) Fixing A Broken Shell Loading Door
=======================================

This is really the only problem you may experience after enough use (by this I mean several thousand rounds on high powered green gas or propane) that I have yet to find a fix for. Occasionally after many thousand rounds the hinges on the shell loading door will break, and unless you are able to contact Maruzen Japan directly for a replacement it is generally impossible to get a replacement shell loading door.
However, based on the size and design of the shell loading door I do believe that a real steel Remington 870 or 1100 shell loading door could be modified to fit with a little cutting and drilling of holes in the right places to fit the Maruzen M1100. This will require further testing and experimentation, but it may be many months before I am able to do so.













Well, that's about it for this article I think! I hope you enjoyed reading it and I hope it serves well to help any Maruzen M1100 owners who may have some kind of problem with their gun :)
MAA Member #83
Every once in a while, when they aren't getting incinerated in lava, crushed under rock slides, or devoured by dragons, goblins experience moments of unmitigated glory in battle.

InSanityPurgeX
Newbie
Posts: 2
Joined: Tue May 16, 2017 4:40 pm

Re: Problem Solving Guide For The Maruzen M1100 Shotgun

Post by InSanityPurgeX » Tue May 16, 2017 4:49 pm

Ello mate,

Soooo I seen your response on the M1100 and felt very excited but agitated as because yes this O-ring trick does solve the feeding issue flawlessly but also starts up another issue of your shells not feeding into the tube, and we all would like to shoot more than just one at a time, as if you can get them in with the oring on the ring doesnt stay where it needs to stay. Also if you use the right size it does not feed properly! if you have actually pictures of what you have done or even the custom ejector replacement i WOULD LOOOVEE!!!! to see it !! :) got the m1100 after a buddy couldnt pay for gas and his idiot dumbass of a buddy broke the magazine tube! lol which ive fixed down to a 4 shell mag.. Just waiting for shop to make a new tube.
Hope to hear back if your still on here!! thanks !!

Touchette
MAA Member
Posts: 842
Joined: Fri Jul 13, 2001 3:01 am
Location: Minneapolis
Contact:

Re: Problem Solving Guide For The Maruzen M1100 Shotgun

Post by Touchette » Wed May 17, 2017 10:11 am

InSanityPurgeX wrote:
Tue May 16, 2017 4:49 pm
...snip...
InSanity, just an FYI but Jin is no longer in the sport of airsoft and TMK does not come around the forums anymore. GL with your gun, there may be other people on the forums with advice, so I'd still check back later just in case.
Touchette
(Pronounced Two-Shay)

InSanityPurgeX
Newbie
Posts: 2
Joined: Tue May 16, 2017 4:40 pm

Re: Problem Solving Guide For The Maruzen M1100 Shotgun

Post by InSanityPurgeX » Sat May 20, 2017 8:41 pm

Touchette wrote:
Wed May 17, 2017 10:11 am
InSanityPurgeX wrote:
Tue May 16, 2017 4:49 pm
...snip...
InSanity, just an FYI but Jin is no longer in the sport of airsoft and TMK does not come around the forums anymore. GL with your gun, there may be other people on the forums with advice, so I'd still check back later just in case.
:( well thats ***** well i kinda figured it was a 50/50 he'd be there or gone.

Post Reply

Return to “Guns Discussion”

Who is online

Users browsing this forum: Bing [Bot] and 1 guest