Hello:
Welcome from the marshes of south Louisiana.
I wish I could help, I only have tube feed Marlin magnums.
Someone should hopefully answer you!

 

I would think if it locks in place, it should be OK. The angle of the magazine follower looks the same. I say try it. My2cents.

 

Don't take this as gospel, but I think the MN mag can be modified to work in the M. A few years ago when I was looking to buy mags for my 25N I came across a lot of posts on other forums, perhaps even here, that stated there was only a slight difference in the old and new mags, but that the difference was enough to cause feeding issues.

You will have to do a bit of research on your own to verify, but I think if you are handy, you can prolly get the newer mags to work.

 

Thanks, guys. I finally stopped being dumb and solved (I hope) my uncertainty. I looked closely at the packaging of one of the vintage OEM Marlin magazines I bought, and saw the 25M listed. So I will be careful trying it, but I assume Marlin knows their own stuff.

Now I just need to figure out how the mag that came with the rifle got so worn.

 

Finally got to the range today. Here's my report on the 3 magazines I own:
1. Original (blued, came with rifle). Fed rounds without problems, no extraction problems.
2. Marlin replacement (blued). Same as the original.
3. Marlin replacement (nickel plated). Fed rounds without problems, but in five cycles of loading and firing this mag I had 3 or 4 extraction failures. Each time I removed the magazine and cycled the bolt, the spent casing ejected fine.

Could be coincidence, but all the extraction failures occurred with the nickel magazine. Does anyone know how a magazine can cause extraction failure?

 

Did you try mag 1 and 2 again AFTER the FTE with mag 3?

The failure may have been a cumulative effect that manifested only after the blued mags were used, making it seem like the nickled mag is the culprit.

If you can, could you post a couple close-up pix of all three mags side by side, from two angles showing the feed lips and follower.

Another suggestion based on FTE issues with the 25N. Inspect the chamber for deformation and burrs.

Also, for clarity, are the spent cases being left in the chamber, or are the being partially extracted, but not ejected?

 

Did you try mag 1 and 2 again AFTER the FTE with mag 3?

The failure may have been a cumulative effect that manifested only after the blued mags were used, making it seem like the nickled mag is the culprit.

If you can, could you post a couple close-up pix of all three mags side by side, from two angles showing the feed lips and follower.

Another suggestion based on FTE issues with the 25N. Inspect the chamber for deformation and burrs.

Also, for clarity, are the spent cases being left in the chamber, or are the being partially extracted, but not ejected?

Thanks for the reply.

Yes, I ran through 3 or 4 cycles with the blued magazines after the last FTE with the nickled mag and had no problems.

In all cases the FTE left the casing in the chamber, not even partially extracted.

I will take a look at the chamber later and get some photos.

 

Sometimes I will use an AI to write what I already know, or to present possibilities that I may not have considered. Below is what Grok3 (Tesla AI, the best IMO) had to say about the problem.

The issue with the nickel-plated magazine causing failures to extract in your Marlin 25M is likely related to differences in the magazine's construction, tolerances, or interaction with the firearm's extractor. Here are some potential causes and steps to diagnose and resolve the issue:

1. Magazine Feed Lip Geometry:
   • Nickel-plated magazines may have slightly different feed lip shapes or tolerances compared to the blued magazine, even if they’re from the same manufacturer. This can affect how the cartridge is presented to the bolt, potentially causing misalignment during feeding or extraction.
   • Check: Compare the feed lips of the nickel-plated magazine to the blued one. Look for differences in angle, width, or wear. If the nickel magazine’s lips are too tight, loose, or misaligned, it could cause improper cartridge positioning.
2. Magazine Follower Issues:
   • The follower in the nickel-plated magazine might be sticking, misaligned, or made of a different material that affects cartridge stacking or feeding. This could lead to inconsistent pressure on the cartridge, impacting extraction.
   • Check: Disassemble the magazine and inspect the follower for burrs, rough edges, or binding. Ensure it moves smoothly. Compare it to the blued magazine’s follower.
3. Spring Tension:
   • The magazine spring in the nickel-plated magazine might be weaker or stronger than the blued one, affecting how cartridges are pushed into position. A weak spring could cause insufficient pressure, leading to poor feeding and extraction issues.
   • Check: Test the spring tension by loading and unloading the magazine. If it feels significantly different from the blued magazine, consider replacing the spring with one matching the blued magazine’s specs.
4. Surface Finish and Friction:
   • The nickel plating may create a slicker or stickier surface compared to the blued finish, depending on the quality of the plating. This could affect how cartridges slide within the magazine or interact with the chamber and extractor.
   • Check: Inspect the interior of the nickel-plated magazine for rough spots or inconsistencies in the plating. Lightly polish any rough areas with fine steel wool or a polishing cloth, being careful not to alter the dimensions.
5. Extractor Compatibility:
   • The failure to extract suggests the extractor claw may not be gripping the spent case properly. If the nickel-plated magazine positions cartridges differently (e.g., higher or lower), it could misalign the case rim with the extractor.
   • Check: Inspect the extractor claw for wear, damage, or debris. Ensure it’s clean and moves freely. Test with the blued magazine to confirm the extractor works consistently, then compare with the nickel magazine.
6. Magazine Fit in the Firearm:
   • The nickel-plated magazine might not seat as securely or align as well in the magazine well due to slight dimensional differences or plating thickness.
   • Check: Ensure the nickel magazine locks in place without wobble. Compare its fit to the blued magazine. If it’s loose, the magazine may need adjustment or replacement.
7. Ammunition Sensitivity:
   • Some magazines are more sensitive to certain ammunition types. If you’re using different ammo brands or loads, the nickel-plated magazine might not handle them as well as the blued one.
   • Check: Test both magazines with the same batch of ammo to rule out ammunition-related issues. Use a proven load that works well with the blued magazine.

Steps to Troubleshoot:

1. Clean and Inspect: Thoroughly clean the nickel-plated magazine, paying attention to the follower, spring, and feed lips. Look for any manufacturing defects or damage.
2. Compare Magazines: Side-by-side, compare the blued and nickel-plated magazines for differences in dimensions, feed lips, follower design, and spring tension.
3. Test with Controlled Variables: Load both magazines with the same ammo and test them in the same shooting session. Note any patterns in the failures (e.g., specific rounds or conditions).
4. Swap Components: If possible, swap the spring and follower between the blued and nickel magazines to see if the issue follows the components.
5. Inspect the Extractor: Clean and examine the extractor and its spring. If it’s worn or damaged, it may need replacement, though this is less likely if the blued magazine works fine.
6. Contact Manufacturer: If the issue persists, contact the magazine manufacturer or Marlin (now under Ruger) for support. The nickel-plated magazine may be out of spec or incompatible.

Likely Culprit:
The most probable cause is a difference in feed lip geometry or follower performance in the nickel-plated magazine, leading to improper cartridge positioning that affects extraction. Start by comparing the magazines closely and testing with the same ammo.

 

I purchased some spare magazines for my 922M, and had trouble with one of them not ejecting the rounds. After a lot of examination, I determined that the rim of the spent round was hitting the front lip of the magazine as the round was being pulled out. This knocked the round off of the extractor claws of the bolt, preventing the extraction. The fix was to file the front lip down for clearance with a half round file. All of the other magazines cleared the rim fine.

 

Thanks. That looks logical to me, and I will try that if nothing else seems to work.

 

Here are some photos with the 3 mags together, from left to right, the original that came with my 25M in 1985, the blued Marlin replacement, and the nickel-plated replacement. The most obvious difference is that both replacements have a little "pouty" lip. But the blued replacement feeds and extracts just fine, even with the lip. By eye, the lip on the nickeled mag looks a little thicker.

 

@BK7070

Did you ever get this worked out?

 

I don't know yet. I made my mods on the new magazines, but have been out of town or busy. I was hoping to get to the local range tomorrow, but my wife just asked for home landscape help. I also just got a pair of Numrich 10 round mags to try.

 

A further report:

I still had FTE problems with the replacement magazines, with the lip blocking the bottom of the rim just enough for the extractor to lose grip. So I went back to the shop and got a bit more aggressive with my files, and tried to make the top of the mags as close to the original 7-shot that came with my 25M in 1985. I did this to the blued Marlin 7-shot and both Numeric 15-shot (I incorrectly called these 10-shot in my previous post). I tweaked the follower bends, and the opening lips at the top of each mag, so the next round presents at the same angle as the original. I also worked on the fit of the Numrich mag side channels that slide onto the receiver tang.

 

And I think I was successful. I stopped at the small range outside of town (a facility managed by Colorado state parks). It was raining so I did not stay long, but I loaded each magazine with 5 rounds (more than once), and ran through all without any feed or extraction issues. Yay!