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Mossberg 151 M(b)

1972 Views 14 Replies 9 Participants Last post by  Mossbergman
Hello All---

Like most I have been lurking for quite some time gathering all the good info I could from a rather enlightened group of people here on RimFireCentral, however recently I have a question of my own that I do not see addressed anywhere.

Recently I was out shooting my old 151 and have a good day at that when I heard a odd noise. I soon found out that my firing pin had broke in two at the secontion where it is cut out for the pin in the bolt. (The most narrow of spots)

I was rather frustrated, however quickly realizing that it most likely was original I quickly calmed. :)

I ordered and recieved a new firing pin to which I promptly installed. Not being a gun smith I was a bit cautious of my efforts, however being a simply firing pin replacement I thought I should be fine.

In fact for some extra security I removed the bullet and powder from a round and simply loaded a primed case to which was promptly stuck by the new pin.

I then headed out to the range to give 'er a good whirl and found things to be going along just fine for the first few rounds. Then i had a jam--- a double feed actually. After clearing that I went on and the same happened a few shots down the road. Finally I was getting to the last 4-5 rounds in the tube when one trigger pull = a double tap. Effectively the rifle shot two rounds automatically, and then stopped. The last two rounds went down range just fine with no jams.

I thought it to be very odd, and rare that the rifle would operate this way so I loaded it again to make sure it could be reproduced. To which I found it can--Simply put the rifle now jams much more often, and almost without fail when getting down to the last 5-6 rounds in the tube fired off a pair instead of a single shot.

I have since taken the rifle apart and thouroughly cleaned it, however the same performance/effect plauges me.

I am currently looking for a smith in the SoCal, Los Angeles area that is familiar with the 151Mb to take a look, however I am simply puzzled how this can be happening as the action of this model rifle is rather straight forward.


This rifle is going into a smith before i take it out again for fear the ATF will have my head if it is thought to be "automatic" due to it's current state.

My questions are:

Has anyone ever experienced this and what was the cause? (Ideas?)

And...

Does anyone know of a smith in my area that has knowledge of these rifles?


Thanks for the help guys and gals!

Dave
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I have a 151M that acts about the same. It may have something to do with the cartridge stop that regulates how the cartridges are fed out of the tube. I don't really know enough to give sound advice but I think if you would search the forum you would find something on this. It may be blasphemy to say this but It could be that this rifle has a natural tendency to do this.
 

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Discussion Starter · #3 ·
afret20 said:
I have a 151M that acts about the same. It may have something to do with the cartridge stop that regulates how the cartridges are fed out of the tube. I don't really know enough to give sound advice but I think if you would search the forum you would find something on this. It may be blasphemy to say this but It could be that this rifle has a natural tendency to do this.
Afret20-

Thanks for the reply, however I have shot 1000s of .22lr rounds through the rifle and never had it "double" on me. I also am used to "frequent" jams, or stovepipes but not at this rate....

I should also note that I tried 5 different makes of .22lr---everything from Velocitors/Varmit loads to normal Remmington HP, Blazer, CCI....
 

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One possible cause of the "double-tap" is the replacement firing pin. If it is even slightly out-of-spec in height or width (or if the firing pin spring is at all weakened by age), the firing pin may be occasionally "binding" in the bolt slot and not fully retracting after a shot is fired.

If the firing pin hangs up in the forward (firing) position, it can create a "slam-fire" when the bolt comes forward, picks up another round and feeds it into the chamber -- the firing pin pinches the rim, and ignites the round, the instant the cartridge is fully chambered. It fires without anyone even touching the trigger.

The fix would be to check the new firing pin and polish/file it everywhere it could bind. Also check for a broken or compressed firing pin spring, and make sure the firing-pin "channel" in the bolt is absolutely clean.

HTH.
 

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I would be almost positive that the problem lies with the new firing pin. It's probably just binding like tony k said. But it could also be a little too long. I'm not sure what the firing pin protrusion should be, but if you can find out and measure it, that may help find the cause. You could try loading it up and firing a round or two, then extracting the next unfired cartridge that cycled into the chamber and inspecting the base of it for evidence of firing pin contact.
 

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Discussion Starter · #6 ·
Thank you both for the very informative posts. It really does make sense now...I guess I simply didn't "want" it to be the pin.

I did try cycling the rifle fully loaded manually via the bolt. After I checked each round for any kind of mark--to which it had none.

It may be binding---Ill give it a polish and see, but if that doesn't do the trick then off to the smith it goes.


Anyone out there know of any in my area, or a good directory to use?

Dave
 

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firing pin fit

Cpt. D-Mossy firing pins may need some fitting to work correctly. I made one to replace a broken pin in my 377(plinkster-70s model) and it worked beautifully. I then picked up a spare on ebay and it would not even fit into the bolt! I had to do considerable filing and stoning to reduce width and height to specs.It still has a problem with jams and need smoothed up a little more.If you still have parts of old pin you might compare them with the new and see if there are any visible discrepencies. Also check that the new pin slides smoothly in the track and does not stick up above the bolt surface when in place (both problems with mine).The good news is that it's not brain surgery and if you are comfortable with hand tools it's not hard to do.Work slowly and carefully and check your work often.Good luck and good shooting-Bruce H
 

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In addition to the pin hanging up in the raceway, it sounds like the trigger-sear connection may have the wrong angle or too little engagement and that the pin may be jarred free by the bolt slamming forward.

Try letting it slam forward on an empty shell several times to see if that may be happening. Also check engagement by pulling the trigger slowly and seeing if there is the same amount of creep before the sear releases.

If you find that it's an engagement problem, that can be easily and inexpensively cured by a decent gunsmith.

Picher
 

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Hamish said:
This makes me wonder...Has anyone ever build a Full auto Mossy .22?
I saw one a few years ago -- a 152 that was registered with BATF as a machine gun and converted in the 1970's. The owner had located some 15-round magazines, which you needed because the rate-of-fire was so high (probably around 1,000 rpm, like most full-auto .22 rimfires) that it emptied a seven-round mag in less than a half-second.

I've been involved in (legal) full-auto shooting for decades, and that's the only full-auto Mossy I have seen or even heard of.
 

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Let me add... Don't worry I have no interest in converting my Mossy to full auto. :D

Intresting stuff though. 1000 Rnds per min is pretty good.
One might have to convert the mag' system for one of those 10/22 bannana mags. Imagine finding one second hand and pulling the trigger for the first time at the range. Blaaaaaaap! :Blasting_ Hehehehe

Oops sorry to hyjack the thread. :angel:

Cheers!
H.
 

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full auto Mossberg

I've seen some papers on the conversion,It was super real easy to do. And it showed how to convert some Hi cap 22 mags to fit. I could not believe how simple it was on the Mossberg design. Ain't tell'n not gonna be a part of some fool gett'n his foot blown off or hauled off to jail.--- :Blasting_
 
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