Odd 7.62x39mm case


#1

What happened here? I found the case on the left at the range the other day. It is a common, Barnaul lacquered steel 7.62x39mm case. Notice how the neck is “stepped”. The case mouth is the same diameter as the normal appearing fired case on the right, but halfway from the case mouth the the shoulder is this step. It seems obvious to me that this case was fire-formed to the chamber of the rifle it was fired in, but the question is what rifle fired it? Is this odd chamber known to be associated with a particular country of origin for 7.62x39mm rifles? It is not a one time fluke thing, as there were dozens and dozens of the exact same cases laying aorund. The funny thing is that sometime earlier this year I read a thread on a firearms forum showing a case just like mine, wondering why it looked this way. This tells me that there are at least TWO 7.62x39mm rifles out there with funny chambers! Any ideas?

AKMS

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#2

I would guess that the case had been reloaded, even though people say that steel cases can’t be, or shouldn’t be reloaded, I’ve run into several instances where people have reloaded 7.62x39 steel caases to make specialty bullets. Like most all of the specialty bullets from Ammotogo / Bigdogammo = reloaded or handloaded Wolf steel cases. Anyway, somebody might have improperly reloaded this case? Too much powder, not enough powder, or improperly placed projectile? And maybe they did it to a whole batch of ammo, and maybe this is why steel shouldn’t be reloaded - it deforms??? Who knows.


#3

AKMS,

this results from an inadequate setting of the gas vent (for this particular load at least). As a result the case already moves out of the chamber while the gas pressure still builds up or is there.


#4

I think it is fired in Saiga.


#5

A close look at the case-head will probably tell you whether it was fired in an AK-type rifle or an SKS-type rifle


#6

This one was fired from a Russian made “SAIGA” self loading rifle (AK clone). The chambers there are widened in the lower neck portion to provide unique id characteristics for forensic investigations. (to distinguish them from AK fired cases).
Sounds odd but this is reality in Russia.
About one year ago there was an article about that in the ECRA bulletin.

Same goes for 7.62x54R cases fired from “civilian” SVD then called “TIGR”. There the widened section of the neck is just a bit shorter.


#7

Thank you Hammer and EOD! I knew there would be an answer here!

Another interesting item to add to the collection…

DK,

Steel cases CAN be reloaded. I have successfully reloaded “Wolf” brand .223 steel cases several times, and have heard of others who have reloaded them up to ten times without issues. Since these cases are boxer primed, it is easy. Most steel cases are berdan primed, making it more difficult to deprime prior to reloading, not to mention the lack of reasonably priced berdan primers here in the US.

AKMS


#8

An interesting topic and some very good replies.

Just to add a footnote to this post. We tend to think of a chamber as just being a hole into which the round fits but actually the dimensioning of a chamber is a complex subject in its own right. A lot of thought and consideration goes into it.

In general military chambers are more sloppy than civilian and tightest of the lot are match and benchrest chambers. This doesn’t even require further explaination I am sure.

The only important part of the 7.62x39 case / chamber is that small band at approx 45 degrees between the case neck and the case proper. That is where the case headspaces in the chamber. That is vital, other than that you can make the chamber as loose as you (reasonably) see fit.

Given the variety and general poor quality of the ammunition in this calibre I can see many advantages in a stepped or loose chamber.

Also, making military cases that are hard to reload by the other side is an intentional design feature. Even more so in theatres where both sides are using the same weapons and that is just about everywhere these days.

Producing a slightly blown case may be seen as desirable.


#9

But the rifles still have to be and are accurate within the standards laid down.

[quote=“Vince Green”]
Also, making military cases that are hard to reload by the other side is an intentional design feature. [/quote]
Can’t agree with that statment at all.

I believe/think the stepped chambers are designed that way for semi auto AK’s for the Russian civilian market so that it is easier for the Russian Police to ID wpns used in crime.


#10

[quote=“Armourer”]

I believe/think the stepped chambers are designed that way for semi auto AK’s for the Russian civilian market so that it is easier for the Russian Police to ID wpns used in crime.[/quote]

Absolutely correct.


#11

That stepped neck would not at all prevent the case from easily being resized with even the most common or simple reloading tools. Decapping the berdan primer would be more of a challenge…and that’s easy enough with the proper tool.

I’d also have to disagree with the statement about poor quality of worldwide 7.62x39mm ammunition. Given the fact that over 50 countries have produced this caliber, it is remarkably interchangeable and of functional quality. Even the Iraqi and Iranian made stuff works, even thought it is visually the poorest quality. I’ve fired many, many thousands of 7.62x39mm cartridges through about a half-dozen different AK and SKS rifles over the past 20+ years. This includes every major maker, both military surplus and comercial that has been available in the US. I can count less than ten ammunition and firearm related failures combined. Two were dud primers from Russian commercial ammunition and several were from a lot of East German short range cartridges where the rim diameter was just slightly too large to fit the bolt of my Soviet made SKS rifle. A few years ago I cleaned out my “extras” box of 7.62x39mm shooter/collector cartridges. I took 75 different cartridges from about 20 different manufacturers/countries and loaded up an RPK drum. Dates ranged from early 1950’s Soviet Mid-East battlefield pickups to currently imported commercial ammunition. some were dirty, dented, slight rust on the steel case, etc. All rounds fired and I was able to keep the group within about 6" diameter at 50 yards firing rapidly from the off-hand position. I credit the design of the cartridge and the AK series for this level of interchangeability and reliability. I would not say that this particular rifle has a “loose” chamber either. Fired cases are not visibly bulged or deformed and they resize very easily. While the AK has some loose tolerances for reliability, the chamber has to be within a certain specification for safety…

AKMS