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Old April 6, 2009, 07:27 PM   #1
Ac1d0v3r1d3
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Mosin Nagant




Sorry for the fuzzy pics, I'm trying to figure out my new camera
As you can see, there was an issue with my mosin. That flat spot on the rim is from the extractor slipping off as the case got stuck in the chamber upon firing.
Once the round had fired the bolt stuck and i had to hammer it open. Then of course the casing was stuck, and i was out in the woods with no ram rod. When i rammed it out last night i noticed that the primer wasn't in the casing.
My Mosin is a model 1944.

And the head stamp on the case is
*
3 10
50


Anyone have an idea as to what happened?
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Old April 6, 2009, 07:44 PM   #2
JasonJ
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check the headspace.. might not be enough room in the chamber
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Old April 6, 2009, 08:04 PM   #3
paladin-34
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7.62 x 54R primers are pritty shallow so it would not surprise me to loose it while pounding the case out. have you been using metal cased ammo in the gun? the varnish comes off in the chamber and this happens. spend some time cleaning the chamber, it may have some well baked on varnish from previous owners also.

Joe
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Old April 6, 2009, 08:15 PM   #4
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On a bolt action rifle (or maybe all rifles, for that matter), when the powder charge explodes in the casing, the primer actually deseats and flies back against the bolt. The gas pressure recoil pushes the casing back against the bolt and into the extractor, reseating the primer. The distance that the round is allowed to fly back by the bolt (called the headspace) needs to be within a certain range for the spent casing to seat in the extractor properly.

This, at least, is my understanding of how headspace works. Problems with it are fairly common in milsurp rifles.

Sounds to me like your headspace is too far; then again, i'm no gunsmith. Check it or have it checked. If you reload your own ammo, i think you can adjust the case length according to the error in your headspace (but i might be mistaken).

Good luck!
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Old April 6, 2009, 09:01 PM   #5
Ac1d0v3r1d3
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So how do i check the head space and what should it be?
I've fired close to 1000 rounds (all brass) out of it in the last 2 years or so and this is the first time I've had a problem like this. So i doubt its from build up from lacquer in the chamber. Also when i bought it, it was "new". Lots of cosmoline but little wear inside the barrel.

Thanks for the quick responses
-Chris
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Old April 6, 2009, 10:02 PM   #6
ferg
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After a 1000 rds in two years, all brass, I'd call this a fluke and not worry about it. If had happened with any frequency, then I'd worry.
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Old April 6, 2009, 10:16 PM   #7
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look for a button on your camera that has a little flower... that's the macro setting. turn it on, and you can take those close up shots
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Old April 6, 2009, 11:00 PM   #8
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Where is the ammo from?

Brass cased or not, you are shooting milsurp ammo, right?

You could just have gotten a bad (overpressure) round. Milsurp ammo, especially in East Bloc calibers can be of dubious origin and quality control.
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Old April 7, 2009, 12:10 AM   #9
Jimro
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acid overide in 1337?

I guess it has a better ring than "crash burn", but srsly "Hackers" wasn't that good.

Jimro
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Old April 7, 2009, 10:31 AM   #10
Ac1d0v3r1d3
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Jimro! Right on, your the first person to actually know what my sn was about. I know the movie really just sucked, but I've been Ac1d0v3r1d3 for almost 10 years, so why quit now?

Yes, all the ammo that I've shot in my mosin has been surplus. And I've had some problems with it before, split cases and the like, but never a problem that may have been caused by my rifle.
I'm not entirely sure where my current lot of ammo is from. If i recall correctly is was 1970's manufacture. Maybe South Africa?
Thanks again
-Chris
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Old April 7, 2009, 11:12 AM   #11
srt 10 jimbo
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Just got my M91/30 Last Saturday. Have not fired it yet, cant get ammo.
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Old April 7, 2009, 03:22 PM   #12
Volucris
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Aimsurplus has tons of ammo available...
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Old April 7, 2009, 03:36 PM   #13
WeedWacker
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Quote:
Sounds to me like your headspace is too far
Not to direct this question at you but for everyone, if it were a headspace

issue being too long, what about too short? I have some silver bear SP's that

seem to fit a little tighter in the chamber than some of the modern brass cased

FMJ (and SP) rounds I use. Almost afraid to shoot them because it takes some

hand work to lock the bolt although it does lock. (Rifle is a M91/59 BTW)
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Old April 7, 2009, 07:14 PM   #14
paladin-34
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You said you had some split cases. Assuming you see the same splitting I do, from the neck of the case down into the first third of the case. If so those splits exist before the round is fired and can be found by side loading the projectile with your thumb as you hold the brass in your hand. Any projectile that moves in the neck during this test has a split case. The problem with split cases is the tiny bits of brass that may be left in the gun when the case splits. Which could have been the cause of your jam.
Clean it good and shoot it again.

Joe
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Old April 7, 2009, 07:15 PM   #15
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Quote:
your the first person to actually know what my sn was about. I know the movie really just sucked, but I've been Ac1d0v3r1d3 for almost 10 years, so why quit now?
I went with the handle "Yojimbo" until some version of Final Fantasy or other introduce my generation to the Ronin for hire as a summon. Just wasn't the same when people thought I was based on a video game instead of the film that inspired "A Fistful of Dollars".

Nothing like an insider pop culture reference. When did we get old?

Jimro
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Old April 7, 2009, 11:58 PM   #16
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The probolem with headspace

Is that the 7.62x54R is a rimmed cartridge. The "headspace" of the rifle is a measure of the space available for the case rim to fit in, and has nothing to do with the size or shape of the rest of the chamber.

Unlike a rimless round, such as the .308 (7.62x51mm/7.62 NATO) which headspaces on the dimension from the base to a point on the case shoulder, checking the headspace on a rimmed round doesn't tell you anything about the rest of the chamber. If the chamber shoulder is too far forward, but the rim dimensions are good, it would pass a check with a headpsace gauge, and still split cases on firing.

The good news is, that if your chamber is excessive or undersize, you will have problems with virtually all the ammo you shoot, not just a round or two.

To be certain of your rifle's chamber, a chamber cast must be made, and then measured against factory specs.

This can be done at home, with a little practice and the right materials, but a good gunsmith should be able to do this, and can check other things (such as the headspace) as well.

Considering all the ammo you have shot, and only had this happen once, I still vote for a bad (overpressure) round.
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Old April 8, 2009, 12:34 PM   #17
Ac1d0v3r1d3
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Quote:
You said you had some split cases. Assuming you see the same splitting I do, from the neck of the case down into the first third of the case. If so those splits exist before the round is fired and can be found by side loading the projectile with your thumb as you hold the brass in your hand. Any projectile that moves in the neck during this test has a split case. The problem with split cases is the tiny bits of brass that may be left in the gun when the case splits. Which could have been the cause of your jam.
Clean it good and shoot it again.
Since, in this case, my ammo is older than i am i generally check each round before i load it. I've found some unfired rounds that had a split from the neck down the side of the case. Those of course i don't load into the gun. But the splits that I've had in fired cases have all been near the base of the case, about 1/3 to 1/4 of the way up.

Jimro, funny, i think of yojimbo as a pocket knife. But yeah i hear what your saying.
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Old April 8, 2009, 09:09 PM   #18
paladin-34
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the chamber needs to be checked. it could just be dirt, or brass peaces creating a gap between the case and chamber (most likely). I’ld scrub the chamber with a well fit brass brush.

Joe
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Old April 9, 2009, 01:26 AM   #19
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Cant tell from the pics but check the brass that you removed with the cleaning rod, if it has scratches along the length of the case you could have rust in the chamber. living in seattle i expect you have more than ordinary humidity.rust could be the problem especially if you put the rifle into a case while it was still warm.
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