I have an odd problem with my M41. Recently the firing pin fell out, and I had a local smith replace the retaining pin. After that, the pistol fired just fine, except for the last round in the magazine.

The last round in the magazine seems to chamber normally, and the slide seems to be in battery. When you pull the trigger, the sound of the hammer dropping is normal, but the gun doesn't discharge. When you rack the slide, that last round is ejected normally, but does not have a dent in it. It can be re-loaded and fired normally as long as it's not the last round in the mag.

If you fire the entire magazine but do not pull the trigger on the last round, carefully remove and re-fill the mag (following all the appropriate safety precautions), re-insert the mag in the pistol, and fire, the "last round" fires normally.

I'm at a loss to explain what is happening here. How can the hammer drop on a chambered round and not drive the firing pin into the round??

The clue to this malfunction is your statement that the "round seems to chamber normally" and that "the slide seems to be in battery". Either the hammer does not hit the firing pin with full force, and no firing pin indent.

The recent firing pin replacement suggests that it may not have been fitted correctly. You should check firing pin protrusion from the breech face.

I would start with a thorough cleaning, starting with the chamber, extractor, and extractor seat. Firing residue under the extractor can frequently prevent the slide from going into battery or cause extraction failures.

Thanks, John. These are all good suggestions. I've already tried the cleaning to no avail. I'll re-check the firing pin, but the fact that all but the last round fire correctly suggests that that's not the problem.

I think this is significant. The fact that the last round fires if you follow this procedure indicates that the round did chamber and the slide did return to battery.

Even though the hammer seems from sound and feel to be falling normally on the last round, it seems improbable to me that it really is. The unfired round appears to be completely untouched- not even a light tap. Could the hammer actually be hanging on something? If so, what?

Can we assume you have tried several different mags? Is it a steel or plastic follower? Have you cleaned mag and checked to see if good spring tension? Fireing pin check is also a good idea as noted above. Assume no shaving on the last round when extracted? As others note, no clear identifyable problem.

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TOMBECK

Thanks, Tom. I only have one mag for the pistol, so I haven't tried any others. It's a steel follower. The mag is clean and seems to have good spring tension, but that's something else for me to check again. Do you have any ideas on how it could cause this problem if the spring were weak?

There's no shaving on the last round when extracted. It appears to be pristine.

A quick look at the internals:
Numrich Gun Parts Corp. - The World's Largest Supplier of Firearms Parts and Accessories
shows that the magazine has a #21: magazine disconnector. It interacts with several other parts in the trigger group. Bottom line, I'd suggest a new, known to be factory, mag. If that works, it's not the disconnector, could be the spring in the older mag. If not, the trigger components need some work.

Thanks, Wiley. I'll be ordering another mag. Ought to have one anyway.

I had a problem similar to this with my first M41, and sold the gun because of it. Even a trip back to the factory did not solve he problem.
Looking back, and with several more years of experience; I now think that I may have had the trigger stop adjusted too far out. Try turning the trigger stop screw one turn inwards and see if that stops the problem. If it does, find a setting that is both reliable and minimizes overtravel. If not, turn it back out to where it was and go to 'plan B'.

Wiley's point relative to possible trigger group being acted on as last round stripped and possible dragging on follower? Different mag (prefer earlier proven one with steel follower) would be my first GUESS.

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TOMBECK

Interesting! I'll try that.

Meanwhile, I have another, unrelated problem with the gun. It'll be a couple days before I get it resolved, so I won't be able to do any more testing until next weekend.

Update: The unrelated problem that I mentioned above was a broken extractor. During the last testing session on the original problem, I had a .22 case fracture when I fired. Most of the case stayed lodged in the chamber. The rear 1/8 inch, including the rim, took off for parts unknown, and the extractor went with it.

This time I decided to work on the gun myself, so I ordered a new extractor and another retaining pin from Numrich. I also got another magazine, a 12-round, from Gunclips. I installed the new parts, but didn't change anything else. Back to the range.

Today I used the gun at the range. Everything worked perfectly, including the last round in the magazine firing. I went through about 100 rounds, with one failure. The last round failed to fire once using the new magazine. There were no failures of any sort with the old magazine.

So, problem solved- kinda. Mystery remains.