MKS Supply offers the answer to the mysterious cartridge groove.
Recently we received inquiries about Barnaul’s .308 Winchester and .30-06 hunting rounds. The .30-06 is an all American round once used by U.S. Forces as a military round but no longer. It is arguably one of the most popular and effective hunting rounds worldwide.
Note relief ring just above cartridge base.
The “mystery” is not really a mystery at all.
The pressure generated by the .30-06 round is higher than other steel cased rounds the company makes. Steel cases are cheap to produce. However, since steel is much harder and less malleable than brass the overall steel case expands slower in the microsecond of gas expansion in the firearm’s chamber than brass cases.
Engineers at Barnaul knew that to accommodate the higher pressure curve of the .30-06 round for that millisecond they needed to accommodate these higher pressures. So, they “simply” designed a slight round groove called a relief ring into the cartridge case near the base. The groove is roll pressed in, there is NO metal removal.
Upon firing the additional pressure will be absorbed and reduced as the relief ring material is pressed out by the powder discharge basically duplicating the expansion of a brass case. Smart, simple, safe and well-engineered.
Barnaul produces the .30-06 using strong polycoated steel cases for reduced cost. Some folks are afraid of steel cases. Read the article linked here at Luckygunner.com ; in a bolt gun it would never cause the problems seen in semi-auto guns. In short, reliability is as good as with reloads.
Barnaul is one of very few privately owned Russian ammunition companies who have been approved to supply their ammunition to the Russian Army. Their high standards and extreme quality control measures have also granted them the privilege to supply the Russian Special Forces with Barnaul’s high-quality ammunition. Their ammo works incredibly well at an affordable price.