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 Marushin UZI ... Basic Troubleshooting Guide

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Cerwyn
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PostSubject: Marushin UZI ... Basic Troubleshooting Guide   Mon Sep 29, 2008 11:28 am

Marushin’s UZI …Troubleshooting

***UNDER CONSTRUCTION***

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1. Rounds failing to ignite
2. Rounds fire but will not extract from chamber
3. Rounds fail to enter the chamber fully
4. Rounds extract but will not eject from the gun
5. Bolt not stripping rounds from the magazine
6. Trigger and Sear


Field Stripping, Cleaning, Inspection and Re-assembly have already been covered in previous Step by Step Guides so this guide aims to pinpoint causes of problems when your UZI refuses to operate correctly.

Marushin’s UZI can be a little difficult at times to fire reliably and consistently. Maintenance and some careful "tuning" can achieve the desired effect but, nevertheless, problems can crop up from time to time.
The ones that do tend to be caused by Maintenance problems or general wear and tear. It is an easy model gun to strip, check and restore to good firing order.


1. Rounds failing to ignite.

Have the cartridges been prepared and loaded correctly?
Are the caps used the correct type and in good condition?

Ref:http://mp40modelguns.forumotion.net/beginner-s-guides-tocartridges-f15/loading-marushin-9mm-mp40-uzi-cartridges-t922.htm
Beginner’s Guide… Loading Marushin 9mm Cartridges

If your Marushin UZI has been converted to fire MGC's P220 cartridges then...
Ref:http://mp40modelguns.forumotion.net/beginner-s-guides-tocartridges-f15/loading-mgc-type-cartridges-t924.htm
Beginner's Guide to... Loading MGC c.p. cartidges

Check condition of Detonator Pin





N.B. This is a custom made Pin suitable for MGC P220 rds

Ensure the Pin is clean and not bent

2. Rounds fire but will not extract from Chamber.

Check that the Detonator Pin and Chamber are clean and not clogged up with Dirt and deposits left from previous firing sessions.
Clogged up Chambers will grab cartridges and stop them being withdrawn by the extractor.

Ref:
Marushin UZI Cleaning and Lubrication http://mp40modelguns.forumotion.net/modelgun-cleaning-guides-f11/marushin-uzi-basic-clean-lubrication-guide-t34.htm


Check the Extractor is working correctly.
Load a round with a “Dead” cap and insert it into the magazine.
Fit the mag’ into the gun, cock it and pull the trigger.
The bolt should strip the round from the mag’ and feed it into the Chamber. It will not fire as the dead cap has no charge so the gun now has the Bolt fully forwards and closed.
As shown here…




Hold the gun level and keeping an eye on the ejection port, slowly pull the bolt back manually by the cocking handle.
The round should be seen to be pulled back out of the chamber as it’s gripped to the bolt face by the Extractor claw.

As shown here…




Ease the bolt back until the round is fully withdrawn.



Look closely to confirm the Extractor’s Claw is hooked onto the cartridge’s rim, like this

Not the easiest thing to photograph Exclamation but peering into the ejection port you should just see the Extractor Claw clipped to the rim like this...




If the round fails to withdraw at all, it may be stuck in the chamber in clogged up dirt.

If the round starts to withdraw, but drops off the bolt face before reaching the Ejector, then there may be a problem with worn out or broken Extractor Claw, Claw Spring, or Bolt Face



Ref:
Marushin UZI Inspection Guide

3.Rounds Fail to enter the Detonator Chamber fully.

First indication of this is the gun failing to fire.
Check that the Bolt has travelled all the way forwards, if you can see the edge of the bolt carrier's ejection port, or into the Receiver through the Port, then the Round has probably jammed up part way in.

Remove the Magazine, has a round failed to eject and is still in the receiver?

Pull the Cocking Lever back slowly, does the round withdraw from the chamber easily?

If it does, then check that Detonator Pin and Chamber are clean… see above

Ensure that cartridges are prepared, lubricated and loaded correctly … see above

Check the hole in the "bullet's" nose. The hole's edges can be damaged by the Detonator Pin as the round is rammed into the Chamber. Burrs or Dents here can reduce the holes diameter stopping the Detonator Pin entering the round all the way in.

See photo...

If the Round remains stuck in the Chamber then remove the magazine,

carefully remove the top plate, the recoil spring may be under tension so be careful the bolt carrier and assembly doesn't fly out

The round will be seen clearly in the Chamber

See photo...

There are 4 possible causes that I'm aware of.

1. Detonator Chamber clogged with dirt residue from firing,
2. Damaged Detonator Pin
3. Cartridge Internals not loaded correctly and have jammed up inside the cartridge
4. The hole in the "bullet's" nose is damaged and has jammed on the Detonator Pin


4.Rounds extract but will not eject from the gun.

Check that the ejector is not bent, loose or broken.



The ejector is secured by a single screw. Remove the Trigger and Grip assembly...



and check that this screw is tight.



Check that the Magazine spring has enough tension to bring the next round up into the gun thereby pushing the fired round out.




Push the carrier down into the magazine body to check for spring pressure(see above photo).

If it feels sloppy or sticks, then dismantle the magazine and check the spring for breakage, rust and the carrier for burrs that may cause friction in the magazine.

5.Bolt not stripping rounds from the Magazine.

Magazine spring too strong… unlikely if it is a Marushin mag’ but possible if using real magazines.
Magazine Feed Lips bent, burred or damaged
Bolt face broken, chipped or otherwise damaged

Ref:
Marushin UZI Inspection of components

Recoil Spring worn out and too weak


6. Trigger and Sear.

Problems here may lead to the gun firing accidentally and uncontrollably or the bolt refusing to move forward when the trigger is pulled.



The Sear moves down into the Lower Receiver when the trigger is squeezed. Ensure it drops into its recess cleanly and that it returns smoothly when the trigger is released.


Ref:
http://mp40modelguns.forumotion.net/modelgun-stripping-and-rebuild-guides-f12/marushin-uzi-basic-strip-down-guide-t14.htm Basic Strip Down
Ref:
http://mp40modelguns.forumotion.net/modelgun-stripping-and-rebuild-guides-f12/marushin-uzi-basic-reassembly-guide-t15.htm Basic Reassembly
Ref:
http://mp40modelguns.forumotion.net/modelgun-caps-cartridges-and-magazines-f6/beginner-s-guide-loading-marushin-9mm-cartridges-t481.htm Loading Marushin 9mm Cartridges
Ref:
http://mp40modelguns.forumotion.net/modelgun-caps-cartridges-and-magazines-f6/beginner-s-guide-loading-mgc-cp-cartridges-t462.htm Loading MGC c.p. type Cartridges
Ref:
Basic Parts Inspection Guide



Cerwyn


Last edited by Cerwyn on Sun Nov 05, 2017 12:54 pm; edited 3 times in total (Reason for editing : images converted to servimg)
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