bushwacker51

German MP-40 Jamming ???

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I just got my original german mp-40. I took it out to shoot and had issues. It only came with one magazine and it is marked mp-41. The weapon does not seem to eject the brass all the way and it lands back in the tube and jams the gun (does not do that all the time also you pull the trigger and it shoves a bullet into the face of the chamber and fails to feed the bullet into the chamber. Alos the bullet gets crammed back into the brass case. I am using winchester white box 9mm. Any help or sugestions would be appriciated. I also might add it jammed twice the last magazine then emptied the rest of the magazine like a champ with no jams Thanks Glenn O.

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Sounds like the mag feed lips need attention, but you don't say whether the rounds are hitting the top or bottom of the breech face as well short cycling too. Hope you are lubing the bolt and the sections of the recoil spring housing which will reduce friction and assist full recoil if the white box is a bit under powered, which it can be. FWIW

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They appear to be hitting the bottom of the breech. Also what ammo would you suggest. Also how do you adjust the feed lips?. Thanks for your help Glenn O. Also I will lube it up better and try again.

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I agree with the suggestion that the feed lips of the magazine could be the feed problem, at least where the cartridges are being jammed into the ramp of the chamber. I've had similar problems with magazines, most recently with a brand new 1911 magazine. With the magazine loaded and out of the gun, tap on the mag and/or gently apply pressure to the rear of the cartridge to see if the round snaps forward slightly, this will cause the round to tip downward when struck by the bolt and result in the bullet being driven back into the case. If this occurs, the lips could be reshaped to correct the problem. 

I used to shoot white box and have not had a problem, with the exception of one round that apparently had a reduced or no powder charge. This was in a handgun, and the bullet cleared the barrel, but not much more, a real problem if it occurs in a subgun. I've shot thousands of rounds of Russian 9mm steel case ammo in HK full autos, and have never had a problem, but have no experience with the MP-40. 

Hope you get it worked out, I've always admired the MP-40. 

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When shooting, I hold the mp40 at the mag well or just above. However, for a few magazines that sit a little loose in the well, I apply a slight bit of forward pressure to the mag so the bullet doesn't nose-dive. hope that helps!

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Thanks for all the responses. I am going to try some different types of ammo. I also ordered a few different magazines. I also field striped the weapon last night and lubed it down with some lsa lube. I also took the ejector out of the bolt for the first time and it had a bunch of old burnt powder and grease packed in the slot and on the back of the  ejector. I don't know if that effects anything but its clean now. Glenn O 

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Going out on a limb here but I was having the same trouble with an UZI and it turned out to be an out of spec barrel. The face of the chamber was wrong and causing the bullets to get smashed back in their cases. Just a thought.


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The MP40 is a pleasure to shoot. They are so smooth they are almost boring.

Sounds like you have two problems. The ejection issue could be the extractor or the ejector. Check the extractor, it should have sharp corners on the tip of the claw. I have an extra original extractor I'll sell you if you need one. The ejector should also have a sharp tip. The ejector doesn't typically go bad, at least not before the extractor. I'd start with replacing the extractor which is a simple remove and replace procedure. It's the combination and timing of the extractor and ejector that throws the spent case from the ejection port.

The second issue sounds like the mag. MP40 can be finicky about mags. They get dropped, beat, bent...hell, they went through at least one war, so no telling what rough use the mag has seen. My advice there would be to buy a couple spare original mags and try them. Mags run about $80 and up.

 

I hope this helps.

Cincylance


The first person someone without a gun calls in an emergency is a person with a gun.

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Sorry for the delay but I bought some like new mp40 magazines from poland. I also used a hotter 9mm and oiled the heck out of the action with LSA. I also shot the older magazine that I bent the lips on and it shot all the magazine except the last round and it jammed. I tryed the new magazines and it  ran like a sewing machine no jams. What a joy to shoot. I love it. Thanks for all the replies and help. Glenn O.

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