WTH happened to this 308 casing?

[WartHog]

Sorting mixed range-pickup brass and found this weird Winchester 308 casing. What caused this and is it safe to reload?

[tabascoz28]

Why chance it for 1 old and battered 308 brass? You sure it is 308 and not 6.5cm? My friend said he just shot a 243 from a 6.5 prc rifle and expanded the hell out of that brass.

[ar15barrels]

Fired in an HK type fluted chamber of a delayed blowback action.



The flutes let the gas go on the OUTSIIDE of the case to equalize the pressure and aid in the case being extracted before the bullet leaves the barrel.

[WartHog]

308 Winchester headstamp - I already decided to throw it in my yellow brass recycling container, just want to know what chewed it up.

[WartHog]

Thanks Randall - what's the purpose of a fluted chamber? Is the casing scrap?

[ar15barrels]

Thanks Randall - what's the purpose of a fluted chamber? Is the casing scrap?

Re-read my updated post above.

Also:

https://thefiringline.com/forums/showpost.php?p=6565060&postcount=3

[justMike]

Reports I have read say that it will reload and function properly.
Probably Randall that said so, but can't say for sure on that.

[J-cat]

It’s hard to resize because the lube runs into the flutes imprinted on the brass and you end up with brass on steel contact in the die.

[DueceMcGurk]

I would 86 it.

[slamfire1]

Re-read my updated post above.

Also:
https://thefiringline.com/forums/sho...60&postcount=3

Great reference Randall!

Let all those who want to understand the principles of automatic weapons read The Machine Gun Vol IV by Chinn. Free from here: http://www.ibiblio.org/hyperwar/USN/ref/MG/

Timing is absolutely critical in automatic mechanisms. You only have a limited time energy is available, and you cannot open the mechanism, and extract the case, when pressure levels are above the sidewall strength of the case.

Which turns out to be, around 650 psia .

This is from Chinn:



for blowbacks, and delayed blowbacks, unlock starts around here



and ends around here:




this is for the M1 Garand gas system, which is not a delayed blow back. But you can see in this chart, that Springfield Armory is measuring the pressure drop, and just when the bolt starts to unlock, and when unlock is complete.



Which is why the pressure curve drop in this AMCP manual picture is so important to measure



The HK91 roller bolts are a delayed/retarded blowback action. The action opens up early in the pressure curve, not so high the sidewalls burst, but still so soon that the case is adhering to the chamber walls. Before the Germans stole the idea from the Russians, high power delayed/retarded blowback mechanism used greased cases, oiled cases, or for the Pedersen rifle, waxed cases.

It is as Chinn says:



I do want to say, this period of firearm history has been largely forgotten, and I think delibrately. I am of the opinion it stems from an Army Coverup of their defective M1903 rifles. Shooters of the period were greasing the bullets of their cupronickel bullets, because the things foul horribly without a grease coating. No one, except the Ordnance Department knew just how defective low number 03's were, and when low number 03's were bursting on the firing line, well the Ordnance Department blaimed the grease. You can understand the logic, perfect Ordnance Department rifles, perfect ammunition, so it has to be the grease. Can't be anything the Ordnance Department did. The idea that grease or oil on the sidewalls of a case, dangerously, and unpredictably, increases bolt thrust has been a fundamental belief within the American shooting community. And I mean fundamental. P.O Ackley built on this, and became famous selling his "improved" straight walled cartridges. Ackley claimed straight sidewalls reduced bolt thrust, and therefore allowed cartridge operating pressures well above proof pressures. I am of the opinion that people believe this, because they are familiar with splitting wood with wedges. Based on this experience, people think the cartridge is a wedge and the chamber is puking out tapered cartridges. His Improved Cartridges did not reduce bolt thrust. Whenever Ackley's famous bolt thrust claims are tested, they are show to be false.

Experimenting with Bolt Thrust

https://gundigest.com/gear-ammo/ammunition/experimenting-with-bolt-thrust

But leading gunwriters were/are in lock step with Ackley, and the US Army. I believe that due to their efforts, they deliberately suppressed or just ignored all the mechanisms that needed lubricated cases. There are literally hundreds that used oilers, pre greased ammunition, waxed ammunition, or other forms of lubrication. To include, chamber flutes. These mechanisms are still out there! The in print crowd really don't understand the function of chamber flutes, or, they know, and don't talk about it. I am of the opinion this cultural ignorance is deliberate, because there are lots and lots of mechanisms that shot trillions of rounds of lubricated ammunition, in combat, and the shooting community is largely unaware of this!


by the way, these are great videos on the early German use of fluted chambers:

Last Ditch Innovation: The Development of the Gerat 06 and Gerat 06H Rifles

https://www.youtube.com/watch?v=WEPwmYcCPFs

WW2 Mauser Becomes Heckler & Koch: the StG-45(M), or Gerat 06H

https://www.youtube.com/watch?v=NrKhJC35QRa

Evolution of the Sturmgewehr: MP43/1, MP43, MP44, and StG44

https://www.youtube.com/watch?v=UXkpFajH66A

I find it interesting that post WW2 Chinn's Machine Series is largely ignorant of fluted chambers. Vol IV does not mention them. So for the period before fluted chambers, what was used to break the friction between case and chambers, was oilers, pre greased ammunition, or waxes. And this is what Chinn says.



Now the most common lubricated machine cannon used in WW2, and was in US inventory up to Vietnam, was the Oerlikon



they are all over the deck



versions were used on aircraft



and by everyone during WW2. The Germans had a version, the Japanese, the British used the same, this 20mm machine cannon was the most produced 20mmm cannon, hundreds of thousands of them built and installed, and the American shooting community is largely ignorant of them.



from Chinn



I did find post WW2, the Naval Department wanted to get the grease out, because you had to pre grease the rounds, grease is messy, etc. And they did try flutes, and teflon, and teflon oiled cases, waxed oiled cases, etc, etc. What they did was to install an oiler on the gun and a bud of mine had and Oerlikon with an oiler bolted to the deck of his armored barge, in Vietnam. I think the American's were not able to duplicate German machining. I have been told flute making is very advanced machining, and it is probable that in the early 1950's, the US did not have that capability. But, I don't know. Maybe an oiler was cheaper.

However, chamber flutes are just great, they break the friction between case and chamber, which results in all mechanism types, more positive and reliable case extraction. And is easier on the extractor, because the case is broken loose from the chamber by gas pressure. It is really a win/win except for the cost.

On all fluted chambers, the flutes stop just at the case head, so there won't be gas leaks around the cases. This is not a problem with greases and oils, I guess peak chamber pressures seal the case.

XTRAXN™ Technology from LaRue Tactical

https://www.larue.com/page/xtraxn-technology-larue-tactical/

these are cases from an XTRAXN rifle.



Notice that Larue does not call the process case lubrication. This is because Hatcherites (those who support the Army cover-up) and Ackleyites are ideologues, in fact, angry, irrational ideologues, and they have a century of industry sponsored pseudo science and lies to back up their beliefs that case lubrication dangerously and unpredictably raise bolt thrust. Arguing the real world with ideologues is unprofitable. I have seen this with Wolf steel case ammunition coated with teflon. This is what Wolf used to say:

Superior Reliability: The application of the polymer creates a precision uniform coating around the casing. It produces a bullet with persistent, uncompromising, stable dimensions thus leading to smooth reliable extractions.

Better Functioning: The superior lubricity improvement eases wear in gun chambers and alleviates excessive operational and maintenance issues associated with rapid firing. The development of this polymer represents a break-through in the field of tribology, and incorporates the most recent chemistry in terms of lubricity improving molecules.

This is what they say now:

Polyformance ammunition will not disappoint! Wolf coats all of their ammunition with a polymer coating to ensure smooth feeding and extraction putting the shooters mind at ease with less jamming. The coating on the ammunition allows for the ammunition to have a lengthier long term shortage time in comparison to different manufacturers

I am certain they have stopped alluding to Polyformance as a lubricant because the the extreme reaction they got from Hatcherites who understand lubrication will "increase bolt thrust". Hatcherites don't know that greases, oils, waxes are also polymers, so using the term polymer, for sintered teflon, won't initiate the mouth foaming you get from this group, that you get with the word lubricant.

There are a few who are pushing back, but they are in the minority.

The myth of over lubrication

https://youtu.be/p9bOT_d60LM

[WartHog]

Thanks guys - I tossed them in with the scrap brass and spent primers I'm collecting to recycle. Have close to 100 lbs so need to figure out who's paying the most in the Bay Area and take it in.

[All3inSD]

Fired in an HK type fluted chamber of a delayed blowback action.



The flutes let the gas go on the OUTSIIDE of the case to equalize the pressure and aid in the case being extracted before the bullet leaves the barrel.

This right here is your answer. I never use brass I want to reload in my delayed blowback rifles.

[Spyder]

POF does that with their trash rifles too, and they claim to have invented it. 😆
Theirs is only on neck and shoulder, not the body, though.

[Citadelgrad87]

Long time HK shooter, those are mostly carbon, and a light dry tumbling will remove any trace of the fluting.

It is safe to reload, I have loaded them 6x and never had a failure in any case.


HKs throw brass to kingdom come, but the myth that they tear up brass is just that, a myth.

[smoothy8500]

It is safe to reload, I have loaded them 6x and never had a failure in any case.....but the myth that they tear up brass is just that, a myth.

I have plenty of HK fired brass reloaded without issues too.