I have a couple friends with a class 3 license that come up to the farm to shoot. Last fall when they were up, one mentioned that he heard a BAR could shoot .308's. With the rest of us safely out of the way, and hopeing it wasnt the last we'd see of a beatifull BAR, he shot the magazine full ,full auto. 20 rounds, went through perfectly! The cases are almost straight, with a tiny bit of taper at the mouth.
I still dont know why that works?? Anyone?

TSJ,
after reading your thread I didn't think it was worth a reply!
but here goes, your mates an IDIOT, perhaps he will kill himself before anyone else.

Griff

griff, the fellow who told him was, at the time, a design engineer at SARCO defense industries. And said they had done it repeatedly. it worked, I dont understand how/why.

Why wouldn't it work? The 308 cas is strighter than the 30-06, so the outer edge of the shoulder of the 308 contacts the chamber wall in the 06 chamber well enough to hold the round back on the bolt face.

This may sound strange however, I have seen this. Well sort of. Competitive shooters around this neck of the woods, are shooting 40 S&W's thru their 10 mm's for practice. All that is happening is that they are fire forming their brass.

At first glance it seems crazy that people would be doing this and still be alive however, by studying the situation and circumstances surrounding this type of practice and the mechanics surrounding case ignition and one starts to relax a bit.

Look at it from this view point. When the powder ignites what happens? The cartridge slams to the rear seating it's self against the bolt face and the brass expands to fill the chamber. If there is an excess gap between the bolt face and the chamber, or the chamber is much larger in diameter that the fired round, then you will have a case rupture due to nonsupport of the brass. This does not happen in this instance. The brass is fully supported so it cannot expand out beyond the safe threshold of the brass case.

The 30-06 chamber is no larger in diameter than the .308 so you have full lateral support of the brass, and since the .308 case shares the exact same head structure as the 30-06 case, then it is doubtful that the case will rupture at the web since it occupies the same area of the chamber as the 30-06 case.

What frightens people is the thought of the head of the brass blowing to pieces. The firing pin protrudes from the bolt face less than .065 inch. When the firing pin ignites the primer, the .308 case only has to move a very tiny distance (less than .065) to safely seat against the bolt face. As the expansion of the brass continues, everything else moves forward and like TSJ has verified, the cases are almost straight. Instant Fireform!

While It may not appear to be the brightest move for folks to engage in this type of activity, having watched the .40 S&W crew doing this in their 10 mm guns and thinking through the mechanics of headspace and chamber support etc, I can see why it works. Granted this is not typical behavior of what we have been taught and I would never endorse such an act, but times are changing and there are those who think of themselves as pioneers...

Malm

Actually, this isn't a new practice. People have been shooting the wrong ammo in guns for a long time. Look at a .357 and .38 ammo. No big deal, but not my bag either.

thanks for the explanation Malm. if you want to see one of the fired cases, I'll send you one.

My guess is that when the 7.62 round was designed, it was test fired in all military weapons that were chambered for the 30-06 round.

Being no expert on this and without really thinking this out wouldn't this be sort fall into the same catagory as fire forming converting the standard 308 round to 308 Ackerley Improved only carrying it one step further to 30/06. I've heard of fire forming 30/06 rounds to 30/06 Ackerly Improved. If memory serves me right I've also heard of fire forming 30/06 rounds to get is it 338/06 brass am I not correct.

Of coarse in making this post I may showing my stupidity on the subject.

I have fired a 308 in a 30-06 chamber and it comes out just exactly like TSJ stated. No big boom, no big flash, just a fire formed big mouth odd ball. (Emphasis on fire formed)

Not quite. You set up to have a good shoulder to headspace on when forming AI cases.

ACT,

A .308 Ackley would be formed in a deliberate and "controlled" manner. Shooting a .308 Win in a rifle chambered for 30-06 would exhibit about as much control and accuracy as throwing a ball in the air and smacking it with a bat.

In the practice of actually fire forming a cartridge, think of the chamber as a precision mould. You place a properly assembled round in this mould and POP, you have a perfect copy of the mould with all the edges and corners where they need to be...

Regards,

Malm

i did the same thing with a 7mm rem in a 7mm stw. the gun was a Ruger no.1 that had been rechamderd. it blew out to the start of the neck on the stw. the case is real thin,and has a tin sound to it.

G.Malmborg

Thanks for clearing that up I think I've learned something, Like I said I was making the statement out of Ignorance. I have not nor would I try or recommend such a stunt without first doing some serious research on the subject.

Malm got me to thinking with the 40 in a 10 mm ...
I remember a fellow shooting 45 ACP in his S&W 45 LC. He would tip the revolver up, to set the shells back in the chamber before fireing.

The 7mm STW headspaces on the belt, and .357 heapspaces on the rim, that's alot different from a 30-06.

Have any of you read the article in Handloader or Rifle magazine about the 7mm blow-up Weatherby rifle? It was published about 2 or 3 years ago. I think it was a 7mm Rem. mag cartridge fired in a 7 Weatherby magnum factory Wby. rifle. It really blew up! The 7mm bullet didn't enter the barrel exactly as required so it became a very effective plug. That caused the chamber to become a "closed bomb test" and it failed. The barrel was split open, scope and stock trashed, etc. Unbelievably, the shooter was not injured very much, if at all.

I've seen 308's fired in Garands lots of times.

Jay, Idaho

Found the article you were probably thinkin of. It's by Ross Seyfried in Rifle 194(March 2001).

The article deals with the aftermath of shooting a 7mm Remington mag in a rifle chambered for a .270 Weatherby Magmum.

The rifle was destroyed but the shooter was ok.

Could this be a case of headspacing on the extractor?
There is not enough taper in the 308 design to headspace on the wide part. The extractor might hold it close enough to keep the rim on! Has anyone sectioned one of those fired vases, (Not cases anymore,) for thickness at the web? What about the concept of the thin part of the brass gripping the chamber before the web area, like all the reloading manuals talk about. I'm pretty sure that headspacing is not to be ignored, while assuming the brass will plaster itself on the bolt before any dimensions change.
T_Bob38, your notion of the front part of the case providing the headspace has merit, possibly would have to be looked at on a chamber to chamber, round to round set of variables. I looked at the cartridge drawings, but don't have the hardware to actually see how far a 308 will go into an '06 chamber with no other parts involved. The required force to do so would be of interest, too.
I don't care how many people casually shoot that way, I would only watch this activity from a safe distance....

[ 01-07-2003, 19:53: Message edited by: BruceHinton ]

>>T_Bob38, your notion of the front part of the case providing the headspace has merit, possibly would have to be looked at on a chamber to chamber, round to round set of variables. I looked at the cartridge drawings, but don't have the hardware to actually see how far a 308 will go into an '06 chamber with no other parts involved. The required force to do so would be of interest, too.
I don't care how many people casually shoot that way, I would only watch this activity from a safe distance....<<

Well, I just tried it in 8 standard 06 chambers. Cases stick out in every one. They go too far in an '06 Ackley improved though.

The BAR fires from an open bolt, and the bolt is heavy enough I think it would chamber a shoe if you could fit it into the magazine. The cases I have show no evidence of high pressure, or that the case head slammed back into the bolt face. I'm certainly not saying it's a good idea, but, it's not as obviously dangerous as first thought.
Again, I'll send a case to someone who likes to measure and compare numbers to see what they come up with.

I have a friend that accidently fired three 300 win rounds at an elk out of his 300 weatherby. He said it sounded wrong and what should have been an easy hit, he believed was an outright miss. His gun smith didn't think he had damaged his weatherby. The thought of MEGA free-bore is a scary thought. I might be ugly but I still like my face more than that.

MEGA free-bore lowers pressures.

Malm

What I want to know is WHY would anyone deliberatly want to do this??

[ 01-08-2003, 05:28: Message edited by: Wstrnhuntr ]

I suspect that the reason that there is not a catastrophic failure is that the 308 case is tight enough in the 30-06 case to seal the case pressure in the chamber. The case is held against the bolt and firing pin by the extractor. The bullet is sufficiently aligned with the bore that the initial primer firing plugs the bore, the case is plastered against the chamber wall by the pressure, hence, the straight wall, fireformed case.

This is not a good thing to do generally. If the pressure gets free, believe me it will play havoc with the rifle and potentially the shooter. I "blew" my 30-338 up by accidentally firing a 30-06 round in it. The 30-06 is much smaller than the magnum case, and the case will burst letting go the gas. The action is not strong enough to retain the gas, and the pressure will blow off things like the extractor and bottom plate. Ugly!

I wouldn't do it. Ku-dude

Interesting discussion. It illustrates that many people lack an understanding of the concept of headspace.

I would think that firing 308's in a 30-06 chamber would eventually result in some nasty erosion of the throat end of the chamber.

Stan,

Good point!

Malm