Cerwyn
Cerwyn (Site Admin)
Number of posts : 11090
Age : 65
Location / Country : North Wales
Registration date : 2008-07-20
 | Subject: Basic Troubleshooting Guide... Marushin MP40  Tue Sep 09, 2008 5:01 pm | |
| Marushin’s MP40 (abs)…Troubleshooting 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 MP40 refuses to operate correctly.Marushin’s MP40 is one of the most reliable and consistent firing pfc model guns available. Failures are generally rare given normal hobby use 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: Beginner’s Guide… Loading Marushin 9mm Cartridges http://www.mp40modelguns.com/forum2/viewtopic.php?t=2264[/b" class="postlink" target="_blank" rel="nofollow">[/i][/color]
Check condition of Detonator Pin
Ensure the Pin is clean and not bent
2. Rounds fire but will not extract from Chamber.
Check that the Detonator Pin and Camber 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Clogged up Chambers will grab cartridges and stop them being withdrawn by the extractor.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 MP40 (ABS) Cleaning and Lubrication…Step 1
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Ease the bolt back until the round is fully withdrawn.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
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 MP40 (ABS) Inspection Guide… Step 2
3.Rounds Fire but fail to Blow Back.
Check that Detonator Pin and Chamber are clean… see above
Ensure that cartridges are prepared, lubricated and loaded correctly … see above
4.Rounds extract but will not eject from the gun.
Check that the ejector has not broken.
Check that the Magazine spring has enough tension to bring the next round up into the gun thereby pushing the fired round out.
Magazine not Feeding rounds up under tension.
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 “prongs” broken, chipped or missing
Ref: Marushin MP40 (ABS) Inspection of components…Step2
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.
Cerwyn | |
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