.30-06 Sprg - Barnaul

[pufik]

Hallo, I have a question, does anybody know why the case has the groove (see picture)? What is the purpose (reason) of this groove? Made in Barnaul. Thanks.

[x]

This groove aids as a extension of the case when the gas pressure is on it's maximum (it gets flattened and adds to the case length). Means the case extends without rupturing in case of too huge head space.

[pufik]

Sorry, but I dont understand how do you mean it? After firing the case will be always extended? Or is it means only like "safety fuse", when the pressure is over maximum?

[x]

Hmm, how shall I explain? The groove wil be flattened out while being fired and the groove will provide for the little length needed to fill the head space. So the additional material comes from that groove instead stretching the regular case wall which may in the worst case rip off the case head.

Was that easier to understand?

[pufik]

Pleas see the picture, is it correctly? if yes I mean I understand... If not, I am sorry :)

[x]

Head space is the distance between the bolt/breeech of the gun and the head of the case.
The marking in your image is pointing to the shoulder.

Please note that in English the "head" of a case is in fact the base, this is confusing but the way the Brits invented the language. So the markings on a case around the primer are called "head stamp".

[pufik]

Wow, YES now I understand. Thank you a lot for angelic patience :)

[x]

You are welcome!