Marushin MP40 (ABS) Firing Problems

Post by romagnus

I am having problems getting mine to fire. Is it possible to get 10 dud caps in a row?
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DPMS AP4 carbine, CZ75, Romanian AK-47, CETME 308, Russian AK-103, XD40SC, 16guage shotgun w/short barrel, Marlin 22LR.....and some others I can't remember right now.....all real. And now a Marushin MP-40

could be the det pin is just to far back an the chamber, the det pin rests on the metal barrel insert which is why getting the position of that is so vital, could be yours has moved or worn and so the det pin is moving back and so no caps going off.

Post by MadMike

It is possible if they got wet or oily I'd say. But it may be a mechanical problem. Is the firing pin / detonator right in its place?
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"It's a hardball world, son. We've gotta keep our heads until this peace craze blows over."

Post by romagnus



it appears to be. The caps are discharged and moved to the opening of the round. I don't get any noise or blowback but the caps seem spent.
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DPMS AP4 carbine, CZ75, Romanian AK-47, CETME 308, Russian AK-103, XD40SC, 16guage shotgun w/short barrel, Marlin 22LR.....and some others I can't remember right now.....all real. And now a Marushin MP-40

That's a strange one! If I've understood you correctly then the cap gets pushed towards the cartridges' firing pin as it enters the Detonator chamber, ignites and slides back towards the cartridges' opening at the "bullet" nose?
If the cap is spent it ignites but there's no noise and the bolt doesn't get blown back?

Is there any sign of smoke?
The vast majority of my Marushin MP40 rounds punch a hole through the cap during firing, What about yours?
It could be possible the caps are just wet or oily enough to allow the charge to burn but without the power needed for BlowBack I guess but if the cap is moving along the cartridge body towards the opening gases are building up in there.

What are you using to lubricate the cartridge bores and cap edges?
Is the Bolt in your gun absolutely free to move along the receiver without sticking?
Is the Extractor doing it's job?

Maybe the Beginner's Guide on... Loading Marushin 9mm cartridges might be helpfull, you might fuind some tips in the Troubleshooting Guide... Marushin MP40 too

Keep us informed as to your progress please, I'm sure we'll get to the bottom of it!

Cerwyn
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Hobby collector of mainly WW2 era uniforms, headgear, field equipment and replica weapons.

Post by romagnus

Ok. After further inspection, this is what I found.

The "bullet" is getting stuck on the firing pin. It appears that the firing pin is punching a hole in the cap and the cap raps around the pin and holds the "bullet" in place. Aside from just cleaning the pin, can I lube the pin or am I just asking for more problems with getting the caps wet? Any advice?
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DPMS AP4 carbine, CZ75, Romanian AK-47, CETME 308, Russian AK-103, XD40SC, 16guage shotgun w/short barrel, Marlin 22LR.....and some others I can't remember right now.....all real. And now a Marushin MP-40

Post by romagus

Ok I got it firing again. I lubed the firing pin and all is well but there doesn't seem to be that big of a bang any more. I will try a different lube and see if that helps.
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DPMS AP4 carbine, CZ75, Romanian AK-47, CETME 308, Russian AK-103, XD40SC, 16guage shotgun w/short barrel, Marlin 22LR.....and some others I can't remember right now.....all real. And now a Marushin MP-40

Hi Romagnus,

Good to hear you got it firing again.

When you saythe cap is sticking to the firing pin are you referring to the pin inside the cartridge or the Detonator pin in the barrel?

Applying a little smear of Lithium grease or Silicone Grease to the edges of the cap should be enough to allow the cap slide back up after ignition.
If the cap is sicking to the Detonator Pin in the barrel I wonder if the either the Det Pin is in need of cleaning, or possibly there may be a problem with the dished washer fitted inside the cartridge.

I know from my early attempts with my own MP40 that not keeping the Det Pin and chamber spotlessly clean had mine jamming up and not eztracting. Removing both pin and chamber showed thy were thick with dirt soot and greasy muck that gummed everything up.
A good scrub with wire wool had the pin gleaming and smooth again which restored the gun to reliable auto firing.

The Det Pin in the barel shouldn't penetrate far enough into the cartridge to pierce the cap and stick to it. The dished washer stops the pin going in too far. It pushes both washer and cap against the cartridges' internal firing pin then acts as a piston pushing back againstthe Det Pin once it ignites sending the bolt backwards.

The Beginner's Guide to Loading Marushin 9mm cartridges will show you how much grease to apply to the cap and the Field Strip Guide will show you how to remove the Detonator chamber and Pin for cleaning.

Let us know how you get on please

Cerwyn
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Hobby collector of mainly WW2 era uniforms, headgear, field equipment and replica weapons.

Post by romagnus

[quote="cerwyn]i'm glad to read your MP40 is firing again What was the cause of the problem in the end?

Cerwyn[/quote]

A very dirty firing pin that sits in the barrel portion. I cleaned it up and got it to shoot again. But today I am running into another problem. I can only pop off 3 - 4 rounds before it stops. Cycle the bolt and it will fire once, cycle the bolt and 3 more go off then stops. I even had a few round not eject and get stuck in the gun. any thoughts?
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DPMS AP4 carbine, CZ75, Romanian AK-47, CETME 308, Russian AK-103, XD40SC, 16guage shotgun w/short barrel, Marlin 22LR.....and some others I can't remember right now.....all real. And now a Marushin MP-40

Hi Romagnus,

A dirty detonator pin will definately cause problems so cleaning both the Pin and the Chamber after each firing session is essential.
To be honest I've found that 2 full magazines will fire without problems but the third mag' will start to foul up due to dirt building up in the chamber and pin.

Another possibility is dirty cartridges. Have you cleaned them thoroughly?
They get very dirty inside and will corrode almost overnight (!) unless you clean them.

Cleaning the Bolt and Extractor, making sure the Bolt and Receiver Tube are lubricated might help too...

Have a read through the Basic Troubleshooting Guide... Marushin MP40 (ABS) in this section. Hopefully it'll help you pinpoint the cause of your problems.

Keep us posted!

Cerwyn
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Hobby collector of mainly WW2 era uniforms, headgear, field equipment and replica weapons.

Post by Claymore

possibly a mag problem as well, is the mag loose at all, mine drops forward slightly so causes feed problems but if i hold the mag it fires fine

Post by romagnus

i put up a video of me shooting it with the problem I am having. Take a look if it will help diagnose the issue.

http://vids.myspace.com/index.cfm?fuseaction=vids.individual&VideoID=24960557
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DPMS AP4 carbine, CZ75, Romanian AK-47, CETME 308, Russian AK-103, XD40SC, 16guage shotgun w/short barrel, Marlin 22LR.....and some others I can't remember right now.....all real. And now a Marushin MP-40

Last edited by romagnus on Sun Dec 30, 2007 1:04 am; edited 1 time in total

Post by Claymore

OK, strange that never known one to fire a burst stop then fire more, is the chamber flush into the barrel if not it could be the barrel insert is not positioned right this is the most important part of the gun as it stops the det pin from moving and absorbs a lot of impact to soften the blow on the bolt, if the barrel insert is not right in then the det chamber will be to high and could cause extraction problems.
There are to indentations in the barrel which the insert fits into did you fit yours into these?
have you tried firing without holding the mag? cant think of anything else that would cause this problem but i will have a look at mine and see if anything else could be a problem

Post by romagnus

ok I figured it out. It turns out that I am just a retard! For some reason when I would load the caps I did everything that the web site here said accept for one important thing.....for some reason I kept putting the dished spacer into the screw in part and not ahead of the cap. I didn't figure out my stupidity until just now, the fourth time I read it.....man I'm slow.

the same link will take you to a new movie of it shooting properly. Notice no more flash from the rounds. Man I'm slow!!!

please let me know what you think of the video.

http://vids.myspace.com/index.cfm?fuseaction=vids.individual&VideoID=24960557
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DPMS AP4 carbine, CZ75, Romanian AK-47, CETME 308, Russian AK-103, XD40SC, 16guage shotgun w/short barrel, Marlin 22LR.....and some others I can't remember right now.....all real. And now a Marushin MP-40

Post by MadMike

Great video, mate! Looks like you are having fun I really like that fact that despite your real guns you are enjoying modelguns.
Maybe I should get me a Marushin MP40 finally ...
_________________
"It's a hardball world, son. We've gotta keep our heads until this peace craze blows over."

Post by Claymore

Glad to see you have solved the problem. great vid i see you had to turn the 40 on its side its amazing how much force those rounds have when they are ejected, when the spring is a bit more used the rounds will come out with a little less force

Post by romagnus

thanks guys. That gun is really fun! I have told my Dad and brother about it and am trying to get them involved also. I just had a lot of fun "building" the gun, the head aches are part of it, and the end result is a blast. Thank you for all the help from everyone.
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DPMS AP4 carbine, CZ75, Romanian AK-47, CETME 308, Russian AK-103, XD40SC, 16guage shotgun w/short barrel, Marlin 22LR.....and some others I can't remember right now.....all real. And now a Marushin MP-40

Post by ljerr2

Yeah, cool video. These darn things bring a smile to your face, don't they? There's something about firing a model gun in full auto.....
So, what's your next model? Maybe a WWII era semi-auto pistol?
Welcome to your next addiction.....

Hey romagnus that MP40 of yours looks OK now doesn't it?! Great to see it firing properly now.

Your video is pretty impressive too! I think it needs moving into the Video section so that browsers find it quickly!
Watching the look of surprise on your face as spent rounds hit your ceiling then dropped onto your head, then turning into a smile of enjoyment was worth seeing!

One thing that struck me was the rate of fire on yours seems slower (and better for it) than mine. Have a look at the vid I posted and see what you think?

Check out Francky's website, he lists Marushin Kits under the Modelguns... Marushin... Marushin long Arms, and also Marushin Kits pages.

Cerwyn
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Hobby collector of mainly WW2 era uniforms, headgear, field equipment and replica weapons.