Marlin 39A problem

[bigbossman]

I have a Marlin 39A lever gun that has an intermittent action problem. Every once in a while the action will lock up when I work the finger lever. The spent casing comes out, the lever extends all the way down in its travel, but locks up solid and refuses to close. Taking the action apart via the thumb screw and putting back together solves the issue (until the next time), but does not give me any insight as to what the problem might be.

Possible clue.... before I take the action apart, I remove the magazine tube and dump all the ammo still in the tube. However, when I dissemble the gun there is always one live round at the base of the tube where it joins the receiver. I remove the bolt/firing pin, and remove the live round before reassembly. I'm thinking that maybe that round is somehow getting stuck and jamming the feed ramp, and removing it relieves the symptom.

Does anyone with experience on this gun have an idea on where the root cause of the failure might lie?

[pennstater]

Hmm. I'll be watching this also. I have and shoot a 39A, and so far, no issues like that. That live round staying in there doesn't sound right. Hmm.

[kendog4570]

Sounds like your problem is coming from the cartridge cut off and its associated components. It should stop the next round in the mag from feeding onto the carrier when the lever is closed and the lifter moves up. Check for a loose cut off screw first. It is on the left side of the receiver towards the front, a little lower than bore center line.

[chp357]

Marlin 39A problem

The problem is most likely an issue with the cartridge cutoff spring. The purpose of this spring is to allow only one cartridge into the receiver per cycle. If it is broken or weak, it can allow a second cartridge into the receiver causing the rifle to jam. Obviously, taking the receiver apart clears it up. There are two different types of cartridge cutoff springs depending on the year of manufacture. Basically, there is a lug on the bolt that depresses the spring when the lever is closed allowing one cartridge to enter the receiver from the magazine tube. As the lever is cycled open, the bolt moves rearward allowing the spring to block the next cartridge in the magazine from entering the receiver. If a second cartridge enters the receiver before the bolt is closed you have the problem you describe. Depending on the year of manufacture, the spring also has a spacer under it that might be missing or installed incorrectly. The problem could be just about anything but this is the first place to start. Take the rifle apart, look at how it works based on my description and gently bend the spring up slightly so it blocks the magazine tube follower when the lever is open. You can manually move the bolt back and forth to see how this works the spring up and down. What i the serial number of the rifle?

[bigbossman]

Serial number of the rifle is V155**.

I have the rifle apart and can clearly see the cutoff spring. The external screw is tight. The spring seems to block the tube follower, but just barely, so I'm guessing a weak or worn spring is causing an occasional round to slip by and jam things up. Can I bend the spring a bit to restore reliable function, or should I replace it?

There is a spacer behind the cutoff spring, but as far as I can see it only goes in one way.... how can it be installed incorrectly?

If I need to replace it, where can I find the parts? Numrich is out of stock.....

[kendog4570]

Brownells has late ones.

[bigbossman]

Brownells has late ones.

Based on my serial number, can you tell me if I need an early one, or a late one?

[alpha_romeo_XV]

The first week that I had my 39A it locked up on the load stroke of the lever. The problem was that I was tilting the gun to watch the next round load and gravity was no longer working on the round the way it needed to. Solution was to always keep the receiver plumb to gravity during cycling. Never had it jam again in 40 years and thousands of rounds.

[bigbossman]

The first week that I had my 39A it locked up on the load stroke of the lever. The problem was that I was tilting the gun to watch the next round load and gravity was no longer working on the round the way it needed to. Solution was to always keep the receiver plumb to gravity during cycling. Never had it jam again in 40 years and thousands of rounds.

That's not the issue I'm having. My problem is when shooting offhand and working the lever as normal.

Coincidentally, yesterday was the first time I loaded up full magazine tubes, so maybe the increased tension caused the next round in the tube to slip past the cut-off spring.

[john myers]

Serial number of the rifle is V155**.

I have the rifle apart and can clearly see the cutoff spring. The external screw is tight. The spring seems to block the tube follower, but just barely, so I'm guessing a weak or worn spring is causing an occasional round to slip by and jam things up. Can I bend the spring a bit to restore reliable function, or should I replace it?

There is a spacer behind the cutoff spring, but as far as I can see it only goes in one way.... how can it be installed incorrectly?

If I need to replace it, where can I find the parts? Numrich is out of stock.....

V prefix in serial number indicates 1961-1962 early-late date appears to be 1975

[bigbossman]

V prefix in serial number indicates 1961-1962 early-late date appears to be 1975

OK, thanks. So, mine is "early" and therefore the Brownells part won't work.

[chp357]

You need an older style. Older ones are harder to find, they are shorter in length compared to the newer style. If you are handy and have a few tools you can order the newer one and reshape it to the exact size of the older one. You can make it the correct size with a grinding wheel, or file, or hacksaw, or any other way you can think of. Gently and carefully shape it to the exact shape of the older one. It's a ten minute job. Or, you can bend the old one gently to better block the magazine entrance when the bolt is open. You can also turn the spacer over and see if that helps but I doubt it will help on your 1962 rifle. The older springs show up on ebay from time to time. Try gently bending it first and see what happens. A steel dental pick or something similar works well for this task. Keep us posted.

[bigbossman]

OK - an update. I tried bending it a bit, and that resulted in a locked up action every time I worked the lever. Obviously I bent it a bit too much. Through trial and error, I bent it to a shape that allows the gun to cycle reliably when empty.

I loaded up a full magazine of 18 dummy rounds, and cycled through somewhere around ejecting round 11 - 12 it locked up again with the lever in the down/bolt open position. Taking it apart clears the problem. Here's what I noticed both times it malfunctioned and I disassembled it....

The remaining rounds in the tube were securely held in place - the spring it well up over the next round rim, so I don't think the spring is the culprit. However - in both cases, a loose round fell out of the action when I separated the halves. So, maybe rounds are double feeding at random? Do you guys still believe the cutoff spring is to blame, or should I be looking elsewhere?

[chp357]

One more thing to check on the cutoff. Obviously, the spring and spacer sit in a milled out recess area. The spring is slightly smaller than the recess so it can sit in the recess slightly cockeyed. It can catch on the edge of the recess if there is a burr or some other flaw. Push up and down on the spring 30-40 times and see if it ever catches on anything. It should be smooth all the time. I would loosen the screw and just make absolutely sure the spring is centered in the recess and moves freely. If it does, then based on your observation, your problem is something other than the cutoff spring. Let us know, we can help.

[bigbossman]

One more thing to check on the cutoff. Obviously, the spring and spacer sit in a milled out recess area. The spring is slightly smaller than the recess so it can sit in the recess slightly cockeyed. It can catch on the edge of the recess if there is a burr or some other flaw. Push up and down on the spring 30-40 times and see if it ever catches on anything. It should be smooth all the time. I would loosen the screw and just make absolutely sure the spring is centered in the recess and moves freely. If it does, then based on your observation, your problem is something other than the cutoff spring. Let us know, we can help.

I saw that possibility, and am using a razor blade as a feeler gauge when tightening the retaining screw.

Another update.... I loaded up the magazine tube again, and reproduced the jam. I dumped the ammo, and then pulled the receiver apart. This time, I think I captured the root cause/culprit...... there was a single round still in the tube, and the rim was just over-riding the lip of the spring.

It looks like the edge of the spring has a lip, and maybe it is either worn or bent. I bent just the tip of the spring up a hair, reassembled, and ran three full 18 round magazine tubes full of ammo through the gun before experiencing the jam again.

I'm going to bend the lip a little further up and see what happens. If I can confirm that the spring is faulty, I have no problem buying a newer spring and shaping it to fit.