Mp40 rattle

That's quite normal, some are worse than others but 99% do it. If you look in the MP40 guides on this weapons section someone mentions about fitting an O-ring around the hop area which helps reducing/stopping the wobble.

Thanks Ian.. I thought that would be the case by looking at the design. I think mine might be one that wobbles more that most.
I've been sitting here looking at it and I think the main problem is just the poor fit of the guide/ retaining rail where it is secured to either side of the mag well. Also the bar not being wide enough to fit snuggly into its guide slot at the front of the gearbox. I'm sure with a bit of tweeking and hammering , I will be able to reduce quite a bit of it.. I'll try the o ring idea also and that hopefully will reduce it a bit more.
Regards Chris.

No worries fella, I got my first Mp40 last year and the wobble was awful, it put me right off the gun and I sold it with never using it, didn't really come on this forum much then, I since bought another second hand one and it only has a little bit of wobble. The guides on the forum are really good, but they give me to many idea's, I've re-wired, fitted a MOSFET, put in new bushings cleaned out the gear box and just got a new tight bore barrel and AK hop to do that conversion, also removed the selector, the small switch in the hand grip and filled and painted the holes that were left. . Once I started I couldn't stop
Good luck with yours any problems that you can't get an answer for on here, just drop us a line and I'll help if I can help.

Having just got in from work and sitting down with a G&T(or few) and taking it apart, the wobble really is mainly down to the poor fit of the pin that fits into the holes on either side of the mag well that holds the locator rail for the two halves, ie. barrel and receiver.. The pin itself simply knocks through and out of the guide rail which means the rail moves freely on the pin.... Therefore if I put a spotweld on each side and stop the movement of the pin it should stop 95% of the wobble and the rail would still move up and down freely.. What do you think... I would have already tried it but my mig went with my last divorce... So a quick trip down to a local welder..
I can easily cope with stock wobble but this is different and driving me mad..
Regards Chris.

try araldite, not as permanent as a weld but it'll let you know how it's going to work out in the long term.

Thanks raffles, I might try that first..
Regards Chris.

It should work. As raffles said araldite or JB weld to try it. I tried to do something similar with the stock but it didn't work so I've got to live with it. Wobbly bits drive me nuts, well accept 2 things lol.

Only thing to look out for is that if you decide to weld later make sure you have an extinguisher or fire blanket handy as epoxy sometimes burns easily and could distort the metal.

Have not welded it yet, but the O' ring does make a big difference.. Good tip..
Thanks Ian...

Glad it worked mate, thanks but I can't take any credit, I can't remember who but one of the other guys on here put the idea forward originally.

is there a pic anywhere of how the o ring fits? and what size o ring?

I just used one that my son had in his tool box.. About a cm roughly, and as for fitting, if you seperate the two halves of the gun and slide the cover back to expose the back end of the hop unit, you will see the hop has a small lip.. It just slides on that lip.. You have to use a little more pressure to push the two parts back together but nothing major.. As for the o ring, I should think most motor factors or even small hardware/car bits shops would have them.. They are usually on a rack with all different sizes and only a few pence each..

no problems with misfeeding/double feeding with the o-ring mod?

Not as yet? Does this fix cause those problems? I've only put about 4 mags worth through it so far but had no problems with it.

Again from memory the only down side was that the O ring could come off easily when taking the gun apart. Also good or bad there was a least one report of a slight increase in FPS.