Mosin case-head sep?


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EmGeeGeorge
January 8, 2011, 01:05 PM
Got a (new to me) 1953 mosin m44...

..took it out yesterday to shoot it...
using old czech ball surplus....

i was worried the firing pin spring might be too weak(which it was)...
It would take a double strike on the primer to fire... so I'd pull the trigger, turn the bolt up, and pull again, so it'd fire...

Just really testing it out...

About the tenth round the back of the case split and vented some hot gases, and particles into my face... I was wearing saety glasses which I always do...

None of the other cartridges showed undo bulging... I have to other mosins than I have had no issues with...

Is this a headspace issue?

Or can your headspace be fine, and a seperation of the cartridge cause this to happen, espacially with 50 year old surplus with thin brass as is...

Also, nothing on the rifle matches serial wise... I know that means tolerances can be an issue...

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SlamFire1
January 8, 2011, 01:32 PM
Really need pictures.

Old ammunition has old powder. Old powder outgases nitric acid gas and that will weaken brass. So maybe that is what happened.

The first picture is of “classic” case head separations. This happens when the brass stretches too much and the case ruptures forward of the thick case head.

The other pictures are of brass flaws. The 223 brass was from Schrach. I believe the stuff was cleaned in an ammonia solution and that caused the cracks right through the thickest parts of the case heads.

Yours, no pictures so no idea.


http://img.photobucket.com/albums/v479/SlamFire/Blowups/308CaseHeadSeperations.jpg

http://img.photobucket.com/albums/v479/SlamFire/Blowups/75Swisssplitcasehead.jpg

http://img.photobucket.com/albums/v479/SlamFire/Blowups/Scharchsectioned223Rembrassblownout.jpg

http://img.photobucket.com/albums/v479/SlamFire/Blowups/LC87ScharchBrassIMG_02070424.jpg

OYE
January 8, 2011, 01:43 PM
Check the headspace for sure.

wrench
January 8, 2011, 05:52 PM
Two things...
First, did the case head separate? Or did the case split? If it was a case head separation, look at headspace. If it was a split case, well, that happens occasionally with old ammo. It's why we always recommend safety glasses.

Second, when you have a round that doesn't fire, rather than lift the bolt handle to recock the bolt, just grab the cocking piece and pull back. That way, if you have a hangfire, you won't have the bolt unlocked if it decides to go off.

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