What is the reason for the groove on the Barnaul .30-06 cartridges case?
What is the reason for the groove on the Barnaul .30-06 cartridges case?
Morten, these grooves are to provide case length by flattening (by gas pressure) so the head does not rip off.
I have examples of these as fired cases (lacquered steel). Some have the groove flattened and some do not. Those with the flattened groove are slightly longer, as would be expected. I’m wondering why the groove does not flatten out every time. Perhaps if the chamber is very tight, there is nowhere for the case to go?
Is the need for this feature unique to the .30-06, intended to be fired in semi-autos? I don’t see it on Russian made steel cased .308 or any other steel cased ammunition, except for the experimental round someone posted a pic of back a few months ago.
The Russians describe this design feature as a measure for high pressure cartridges, seems the .308 does not need it. The other ones having this were the experimental 6x49 and 6x57 cartridges.
That there are flattened out grooves and not flattened out ones I think is a result of differing head space. Rifles with a tight head space do not allow the grooves to flatten out. Those that do have likely a wider head space and save the case from rupturing - as the Russians intended it to be.
Not sure if the case shown is brass washed steel, or just brass as I don’t have one in my collection so I can check. However the lacquered steel cased rounds have this groove and it is found in atleast two different distances from the base (the one shown by Morten is the higher/ longer distance).
The Rusians also made the lacquered steel case without the groove, and I have a fired example where the head material has “flowed” or moved into the breech/bolt face, creating a lip on one side, just above the extraction groove or rim undercut.
edited one to note groove placement
The fired cases I have with both the falttened groove and un-flattened groove were all fired in the same rifle. The headspace issue does not seem to apply here, although it seems to be the logical reason. It should be noted that these lacquered steel cased rounds use a powder that is not compatable with use in the M-1 Garand rifle. When fired in the Garand, this ammunition creates a huge fireball and a very violent operation of the action.
I was noting a steel case originally made without an expantion groove.
I’ve no idea what weapon it was fired in, but I think you are correct that it does not appear to be a headspace issue with my fired (not originally grooved) case.
I think this non-grooved case was one of my earliest steel cased Russian 06 rounds. The non-grooved headstamp notes it as a “30-06 SPRG” while my other grooved rounds simply use “30-06”.
I have 3 kinds of these cases in my collection:
varnished steel case
zinc washed steel
brass washed steel
all of them have the groove at the base
We got a few cases of this surplus stuff at our shooting club last year. Talk about a bad investment, even if it was dead cheap.
Steel-Cased Bernaud ammo caused problems in just about every gun it was fired in… Way too hot and unreliable for use in older firearms. I advised against using it from day 1, but as it usually goes, things have to break first before people start taking notice…
M1 Garands developing feeding issues and double shots with the 30-06.
Damaged SIG PE90 with 5,56 steel cased ammo.
Damaged Colt AR15 with 5,56 steel cased ammo.
[quote=“AKMS”]The fired cases I have with both the falttened groove and un-flattened groove were all fired in the same rifle. The headspace issue does not seem to apply here, although it seems to be the logical reason. It should be noted that these lacquered steel cased rounds use a powder that is not compatable with use in the M-1 Garand rifle. When fired in the Garand, this ammunition creates a huge fireball and a very violent operation of the action.
Strange, no idea how this happened, are the loads of these cartridges all the same or do they vary in weight - means they might be inaccurate and cause the gas pressure to jump?
Thanks all of you.
Forgot to say that the case is brass washed steel, and here is the headstamp:
I have the 30-06 and the (experimental)Simonov cartridge
I do not know if the loads are inaccurate or have varying charge weights. I do know that the powder is not appropriate for use in gas operated semi-automatic rifles like the M-1 Garand. Some of my rifle team mates tried this Barnaul .30-06 and experienced heavy recoil, violent operation of the action and a huge “fireball” at the muzzle!
I have not had any problems with any other Russian steel cased ammunition. I’ve fired a lot of steel cased .223 and even reloaded some of the cases a few times. The “WOLF” .30 carbine worked well in two different rifles and of course the 7.62x39mm and 5.45x39mm are quite reliable. I have no problem with the steel cased ammunition except that it is now almost as expensive as brass cased!
EOD - regarding the poor performance of the Russian .30-06 in rifles like the M1 Garand, it may have nothing to do with anything other than simply a powder not suitable for the piston system of the M1. It sounds to me like the problem with the ammunition for those rifles is not chamber pressure, but rather port pressure; that is, the pressure still generated as the bullet passes over the gas port near the front of the barrel. If port pressure is too high, even though chamber pressure is at perfectly safe levels, you can get violent performance and even a damaged operating rod in a long recoil system like the Garand. It does not have any good way to bleed off an excess of gas as does the short-stroke piston in, say, the M14 rifle, which bleeds of excess gas thru a hole that is uncovered as the piston moves rearward to strike the operating rod. Every bit of gas that flows into the gas cylinder of the M1 reacts against the piston.
John, thanks for the explanation, I never knew about this connection.
I just started to read this thread since the title did not indicate anything I was interested in.
You guys may already have gone onto other things but, has anyone considered that this particular case design was intended to operate the action of the weapon? IOW, the case would lengthen upon firing, transmitting a rearward movement to the bolt and locking mechanism thereby doing away with the need for recoil, gas, etc to operate the weapon.
I believe Maxim experimented with such a design many, many years ago.
Or, maybe I’m way off base.
Ray, IMHO I think the case lengthening process does not provide any of the required momentum.
I’m not claiming that this particular 30-06 cartridge is/was intended to operate the rifle’s mechanism, but there would be more than enough momentum, in my own HO. Look at Garand’s primer activated design. Go to my most recent thread on the SCHV/SALVO/SPIW cartridges and look at that XM110 Single Flechette cartridge. It’s unique primer design is what provided the energy to operate the weapon.
I just remembered that this question was hashed out before on this Forum, about the Barnaul .30-06’s groove at the base of the case. The final consensus, taken from advice given by a Russian Lady at a Barnaul booth at a European trade show, and from comments from a Russian manual, is theat the groove was done to strengthen the case in high pressure cartridges. Not a totally satisfactory answer, since other high pressure cases on Russian ammo don’t seem to have it. However, that’s what it says.
The Thread, “Barnaul 30-06???” was on May 18, 2007. It is best searched using this Forums “Search” feature by simply searching “Barnaul” as adding the caliber will bring up every thread that mentioned the .30-06 cartridge.
Those interested might want to review it.
At another Barnaul booth at another European trade show, the staff claimed that the groove was to aid extraction by increasing the ability of the steel case to “spring back” after firing rather than gripping the chamber walls. Another “not a totally satisfactory answer” but given the length of the 30-06 case body this sounds more feasible than the suggestion that it is to strengthen the case due to high pressures. But, like John, I remain a skeptic !
Staff at trade shows are picked for their ability to look good and speak the local language - not for their knowledge of the production process.
Barnaul’s initial 30-06 steel case production (1990) did not have these grooves.