M39 Magazine Feeding Problem

[Enfield47]

I've been experiencing a feeding problem with my M39, the interruptor (not sure if that is what it is called) has been getting caught under the edge of the magazine after firing a single shot. This causes the remaining rounds in the magazine to tilt upwards so they won't go into battery. When I originally load the magazine, the rounds will click below the interruptor and be properly held in place. The first round will feed correctly, but after that shot is fired and the bolt pulled back, the remaining rounds will then have the bullet tips forced upwards.

When I loosen the two guard screws, it will pop back into place. I have tightened down both guard screws as tight as I can get them but under recoil the problem repeats. I am at a loss as to how to fix this. Do I need to pull the action from the stock and file down the edge of the magazine where it is getting hung up? I don't think that's the best solution, since the rifle functioned properly before. If the magazine has somehow shifted, how do I adjust it?

Any ideas on how to fix this problem?

Here are couple of pictures of the part that is getting forced under the edge of the magazine. The problem is not occurring in the pictures but you can see how close it is to the edge of the magazine that it is getting caught under.

[Vlad 11]

That tab is part of the interrupter spring, the tab serving as a cartridge hold down. The spring sits in a slot in the receiver... it can move fore and aft if the screw is loose or missing, so id check that first. Could also be bent spring or mag shimming issue or bolt interfering somehow

Either way take the action out of the stick and check it out. You can assemble the mag and action outside of the stock to function test. That will give a good indication of what is happening with the geometry and help determine what is out of spec.

[6mmintl]

Disassemble and CLEAN off all the cosmo, stone all worn surfaces and ramp/polish the top radiused surface of mag disconnector.

Looks like the mag box is rubbing the tab/cartridge stop towards the back of mag box, stone that area after identifying "Rub" marks and add maybe .010" more clearance by carefully filing/stoning.

Ramp/polish rear of mag box where cartridge rim hits top/back of mag well.

[Flyin Brian]

There needs to be 1 to 3mm clearance between the top of the magazine and the bottom of the receiver. If you don't have the 1mm when you tighten the action screws, you need to add shims to the magazine housing to move it down a bit. I have a graphic on my office computer that shows where to shim but it soul be pretty self explanatory.

[Flyin Brian]

Found it- green is where the space needs to be, red is where the shims go

[SMarquez]

Bryan, is this a new problem with this rifle?

[OniKoroshi]

OP did you over tighten the guard screws and now the stock is compressed?

[81turbota]

Hello- based on what I saw in person, it seems like either:
- your magazine well is shifted by either lack of shims or stock bedding
- interrupter spring has popped out of place, it attaches to the receiver with a small screw

If this is the first time you're having this problem, and it has functioned fine before I don't thing filing and cutting is the solution. Good luck! Let us know what you find.

[Enfield47]

Thanks for replies, I'll take the action out of the stock tomorrow and see how everything looks. I had this problem the last time I took it out, but it was right at the end of the shoot and functioned fine until then. One thing that did happen on that shoot was the guard screws both came loose and after tightening them the problem started occurring. I didn't crank the screws down, just tightened as normal (until I started to feel resistance).

It does have the metal shims at the points noted in the picture so I'll measure the clearance between the magazine and receiver before and after I remove it and replace it in the stock.

[OniKoroshi]

Enfield, from the first pic you posted it looks like the rear screw is too tight. I'm basing my assumption by the magazine woodline and gap. It could also just be the angle of the picture.

[81turbota]

Thanks for replies, I'll take the action out of the stock tomorrow and see how everything looks. I had this problem the last time I took it out, but it was right at the end of the shoot and functioned fine until then. One thing that did happen on that shoot was the guard screws both came loose and after tightening them the problem started occurring. I didn't crank the screws down, just tightened as normal (until I started to feel resistance).

It does have the metal shims at the points noted in the picture so I'll measure the clearance between the magazine and receiver before and after I remove it and replace it in the stock.

If it jammed up when you re-tightened the action, I am almost 100% certain at one point in the rifle's life a shim or two was lost. My money is on re shimming the magazine well.

Shims can be made from brass, or can be bought for $10 or so online pre stamped.

[Enfield47]

I got everything taken apart. I tried to measure the gap between the magazine and the receiver but was unable to get my calipers in there. I used a toothpick to help gauge the gap and it was about 3mm.

Here is a photo of some minor damage to the outside of the magazine, it's pretty minor, but still visible. There was no visible damage to the interrupter.





Here is a picture of the bottom of the stock where the magazine sits. It has made a couple of dimples in the wood from the heads of the rivets. Is this how it should look?





There are no shims around the magazine, they are only located where the guard screws are in the front and rear of the receiver.

[Flyin Brian]

You said in a previous post that there were shims in the location noted in the graphic I posted, but now you are saying there are no shims there. I am thinking you are getting mixed up with the shims that are under the recoil lug/tang area.

Take another look at the graphic and you will see it is showing the red areas are the areas where the magazine fits into the stock... the same as what you are showing in your most recent photos. Cut a piece of plastic from a credit card, plastic hotel room key, casino player's club card, whatever you have available, and stick it in the rear slot where the magazine fits into the stock.
The reason why I am saying to focus on the rear is that if the front is too tight, the front of the magazine will run into the bottom of the bolt head when working the bolt, and you did not mention having this issue, so I am betting the rear is where the mag housing is sitting into the stock too far.

As for the marks on your stock, it is perfectly normal for a post-war stock, as the stocks are much thicker than older stocks. I grabbed these out of my safe; a post-war 1968 M39 with square joints and a PW Tikka in a transitional stock, and both look like yours:

[Enfield47]

Brian, sorry, yes I confused the shim locations. There are no shims where the magazine fits into the stock. Just from looking at the stock, it doesn't look like any shims were present when it was put in the post-war stock. I have a plastic card that I can cut to fit into the locations noted into your drawing.

Here are a couple of pics of the front and rear from the top of the magazine. It looks like the front of the magazine has some wear where the finish has been worn off. The rear looks a little worn too but the finish there is mostly in tact.





I have owned the rifle for about a year and only taken it out shooting 3 times and haven't put many rounds through it due to feeding problems. The previous owner had a problem with the bolt sticking after firing. I thought I had fixed this problem by fully cleaning out the bolt of old comso since it operates easier now than when I got it. Is the wear on the front of the magazine indicative of that problem?

[Flyin Brian]

I couldn't say if that wear is from the mag hitting, I just know if it hits you will know something is wrong immediately since the bolt won't pull back

IIRC, the front edge of the magazine works sort of like a pre-feed ramp, so it sits up and inside of the opening in the bottom of the receiver. If your magazine inletting in the stock is too deep, that front lip will hit the bottom of the receiver, so that could be contributing to the shiny spot on the front of the mag lip.

I know I have a few Mosins in the safe with metal shims in the stock to space the magazine out a bit... I just can't seem to figure out which one(s) it could be... I wasted an hour going through the safe trying to find one!! LOL I hate it when you know you have something and can't locate it.

FOUND IT!!

This one is a 1926 Tula "Big Hammer" Dragoon with magazine shims on it. Interestingly, it was not a Finn capture, and it didn't stay in the USSR or else it would have been upgraded from a Dragoon to a 91-30, so it's been somewhere else until it came to me: