7.62x54R Issue (w/ pics)

[DerFreischutz]

Soon after I got my first Mosin Nagant, I picked up some cheap surplus at a gun show. I think it's 1952 Bulgarian light ball. It looks really dirty and when I shoot it, sometimes I get "blowback" in my face. It's not harmful, but anticipating it makes being accurate difficult. I stopped shooting it for a few years, but decided to give it another go this weekend. It happened on one out of five rounds. Here are the pictures. What exactly is happening? What term should I Google to get more information? Thanks for any help.

 

[lovemywoods]

It appears that the casing has cracked in several uniform splits all around the casing near the head. I find it interesting that the cracks seem very similar to one another making me think it may be related to the original manufacture of the brass casing (the forming process).

When the round fires, hot gasses are expelled. Since it is behind the area where the casing is normally sealed against the walls of the chamber (due to pressure), the gasses vent around the bolt and eventually to your face!

There are many very knowledgeable people here on INGO that hopefully will chime in.

Please keep us posted on what you find!

 

[Mosinguy]

double post

 

[Mosinguy]

It appears that the casing has cracked in several uniform splits all around the casing near the head. I find it interesting that the cracks seem very similar to one another making me think it may be related to the original manufacture of the brass casing (the forming process).

When the round fires, hot gasses are expelled. Since it is behind the area where the casing is normally sealed against the walls of the chamber (due to pressure), the gasses vent around the bolt and eventually to your face!

There are many very knowledgeable people here on INGO that hopefully will chime in.

Please keep us posted on what you find!

^this

 

[Shoots4Fun]

Lovemywoods had good observations. Personally, I'd buy some newer ammo. Not being sarcastic, but I wouldn't want to shoot that stuff. The shells look pretty aged and there's a lot of powder in those 7.62 x 54r.

My ...

 

[turnerdye1]

Yea i wouldnt want to shoot those rounds. It only takes one bad one to blow up in your face...literally. I would pull the bullets and sell them to people who reload that round. That way the money you put into buying the rounds isnt a complete waste.

 

[xring62]

Ive seen one crack such as this on the shoulder but never nothing like those pics. Ive had trouble out of 54' in 20 round boxes,overpressure,split necks..., but never the 'bundled' in the spam cans

 

[DerFreischutz]

Thanks for the replies. I should mention that I've tried this ammo in two different Mosins with the same results. Also, the only reason I tried it again recently was because this time, I carefully inspected every case I shot. Before, I would load without taking note of damage (which in hindsight was dumb). But as the pics show, even cases which look OK are too risky. I will be selling to rounds to a reloader as soon as possible. I would much rather have 10 safe rounds than my current 200+ dangerous rounds.

 

[johntheplinker]

Early 50's Bulgarian is not very good ammo. Some of the cases were made from a poor quality brass that tends to crack instead of expand due to being bad to start with and because of its age. Some of it was even made from reformed 8x56r cases that were simply resized. That stuff has thin, slightly small rims as well.

 

[the1kidd03]

rounds are very likely poor quality....but you should also check the head spacing....similar results can come from head space problems caused by either the rounds or the gun itself

 

[the1kidd03]

being that they are military surplus rifles....it's most likely a head space issue....surplus rifles have had thousands of rounds through them and so tolerances have most likely deviated from the original manufacturing specifications. These deviations can include but are not limited to: throat erosion, worn rifling, and headspace issues. insufficient headspace can lead to the exact symptoms which you have described

 

[DerFreischutz]

I won't deny that it may be related to headspace, but I've run probably 6 other types of surplus (Russian, Czech, Yugo, Polish, etc.) as well as some Prvi Paritzan through my Mosins and never had any type of issue at all (no FTF, no blowback, nothing). I feel safe shooting the guns, just not with this ammo.

 

[the1kidd03]

the ammo can cause the headspace issue.....take a pair of calipers to the rim of a brand new match grade round and compare that to the rim of the crappy ammo you're having problems with...it could be thicker for an array of reasons which would create the necessary gap....in this case it would be the ammo obviously, but at least you would know 100% what the issue is.....I'm limited in my ability to advise from just pictures and not having a round in front of me to test

 

[DerFreischutz]

the ammo can cause the headspace issue.....take a pair of calipers to the rim of a brand new match grade round and compare that to the rim of the crappy ammo you're having problems with...it could be thicker for an array of reasons which would create the necessary gap....in this case it would be the ammo obviously, but at least you would know 100% what the issue is

That makes a lot of sense. What rim thickness variance would concern you? I will see if I can get a hold of some decent calipers to check the thickness. Maybe I'll head over to Applied Ballistics and try to borrow some for quick second.

 

[the1kidd03]

thermal expansion, crappy quality of brass having other metals in it and corroding, etc...could all cause the rim to be thicker than the gun can/should handle.....also, when you use newer ammo in the same gun it could also be manufactured to the heavier side of the ammo specs which would fill in the headspace gap and prevent the blowback problem...this would indicate a very slight amount of wear on the bolt face and it is still possible.....which is why I would still recommend having the head space checked

 

[the1kidd03]

it's really just simple math....try to look up factory specs on the weapon models headspace...usually military rifles have a wider tolerance than better quality weapons because they want them to be able to shoot "anything" out of them.....but on top of that you would have to measure the space in the chamber which I don't know the place you spoke of, but they may not have the necessary tools to measure the chamber...and then do a little subtracting and you will know if the ammo is causing problems or if you do have a worn bolt face or a little of both

 

[the1kidd03]

get yourself a $25 no-go gauge...place it in the bolt and try to close it....if it closes all the way...then it is definitely the bolt and you need to take it to a REAL gunsmith...not one of those guys who runs a gun shop, says he's "certified" and claims to be a gunsmith.....if someone claims to be doesn't have at least a lathe, TIG welder, and a mill ...then he's not a true gunsmith

 

[johntheplinker]

the ammo can cause the headspace issue.....take a pair of calipers to the rim of a brand new match grade round and compare that to the rim of the crappy ammo you're having problems with...it could be thicker for an array of reasons which would create the necessary gap.

thermal expansion, crappy quality of brass having other metals in it and corroding, etc...could all cause the rim to be thicker than the gun can/should handle.....also, when you use newer ammo in the same gun it could also be manufactured to the heavier side of the ammo specs which would fill in the headspace gap and prevent the blowback problem...this would indicate a very slight amount of wear on the bolt face and it is still possible.....which is why I would still recommend having the head space checked

Since the 7.62x54r round is rimmed a thicker rim would cause insufficient headspace. A thinner rim would, on the other hand, could cause excessive headspace. I've shot some of this ammo in the past, and had quite a few problems with it. It is just old, bad ammo that should be junked.

 

[longbow]

I would have stopped shooting that ammo after the second time it happened.

Save it for hand outs when the SHTF?

 

[pinshooter45]

Since you don't have this problem with other surplus ammo, and this ammo does the same thing in other Mosins, the trobleshooter in me says it's bad ammo! If it was only doing this in the one rifle, then I'd say it's the rifle. But the constant seems to be the ammo no matter what rifle it's fired in. I personally would dispose of the ammo. But these Mosins are built like a tank so You might be ok to use it up depending on how much you have left, but to me the risks out weigh the benifits. I would not want to take the chance of some of this ammo blowing something back into my face or damaging a nice Mosin. Just my 20+ years of trobleshooting !