What would happen if you touched off a .308 in a .30-06 chamber?

H4831 said:
OK, I had thought the 308 case was short enough that it would not seal the chamber and gas would escape. However, it appears long enough to seal the chamber.
Rookie Wildcat, you said, "The .308 is a cut down .30-06. Therefore the case is basically the same size all the way to the .308 shoulder. The length of the brass case is long enough to actually reach the .30-06 shoulder. How does this make it practically impossible to chamber? Did you think about that statement?"

The 308 is quite a bit different than a cut down 30-06. It must be a very sloppy chamber in a 30-06, to easily accept a 308 round.
A 30-06 case is .4698" above the rim, while a 308 is .4703". That's .005" right at the solid part of the case, so the 30-06 chamber would have to be that much too large, for the 308 case to go in.
However, at the shoulder, the 308 case is .013" larger and that is a considerable amount in a rifle chamber, .441" against .454" for the 308.
I can see a military 30-06 having a large enough chamber to accept a 308. However, I have just measured empty 30-06 cases fired in a Husqvarna and a BSA. The average size at the shoulder is .444 of the empties from those two commercial rifles. Thus, it would take considerable power, certaily abnormal power, to force a 308 cartridge into either of those two rifles of mine.
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Interesting. I'll bet that is one of the reason it fires. If you do manage to get the .308 to fit in, the back of the case would be forced firmly against the bolt face giving the firing pin a firm strike and igniting the primer. From everything mentionned in this thread, it looks like it was purposely engineered to do just that because the military had the forethought that this would likely happen on a repeated basis.
 
Thus, it would take considerable power, certaily abnormal power, to force a 308 cartridge into either of those two rifles of mine.
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It sure didn't take much effort to chamber a factory .308 Win cartridge into buddy's Savage .30-06, at least not enough to indicate something was amiss. A careless moment could have had disasterous results...
 
The 308 case is actually of a slightly greater diameter at its shoulder than the 06 case at the same distance from the rim. This is because the 308 was developed using the 300 Savage rather than the 06. I think that this difference, especially in a tight chamber would probably keep the cartridge from being driven further into the chamber by the firing pin and the the likely result would be separation of the neck portion of the case. It might not do anything other than fireform the case into a very short 06. Please don't experiment.
 
There were many Remington Rolling Blocks sold in "7mm" over the years. I know a guy who bought one for a donor action to build a .40-65. The owners would assume it was 7x57 Mauser. Turns out they weren't, but 7x57's would go bang, problem is it would mangle the case, and pierce the primer. There was an article in the Black Powder Cartridge News about this and what the true calibre was.

And I have seen a Remington 7600 in .270 that swallowed a .308 Winchester. Funny story because it involves dimwits, two identical rifles save for the chamberings, a heated deer hunt, and no personal involvement on my part.
 
I just witnessed a guy squeeze off 3 rounds of 7mm Rem Mag out of his custom Mauser action chambered for 300 Win Mag last weekend. couldn't hit the huge target at 200 yards, bullets were landing beside the target in the wet grass. I was checking to see if his mounts were loose and I noticed the brass was splitting, and fire forming to his chamber. He then proceeded to shoot a nice tight 3 shot group with the correct ammo.
 
H4831 said:
Rookie Wildcat, you said, "The .308 is a cut down .30-06. Therefore the case is basically the same size all the way to the .308 shoulder. The length of the brass case is long enough to actually reach the .30-06 shoulder. How does this make it practically impossible to chamber? Did you think about that statement?"

The 308 is quite a bit different than a cut down 30-06. It must be a very sloppy chamber in a 30-06, to easily accept a 308 round.
A 30-06 case is .4698" above the rim, while a 308 is .4703". That's .005" right at the solid part of the case, so the 30-06 chamber would have to be that much too large, for the 308 case to go in.
However, at the shoulder, the 308 case is .013" larger and that is a considerable amount in a rifle chamber, .441" against .454" for the 308.
I can see a military 30-06 having a large enough chamber to accept a 308. However, I have just measured empty 30-06 cases fired in a Husqvarna and a BSA. The average size at the shoulder is .444 of the empties from those two commercial rifles. Thus, it would take considerable power, certaily abnormal power, to force a 308 cartridge into either of those two rifles of mine.
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Not sure where you got your measurements or your math, that's actually .4703-.4698=.0005" not .005" I don't think that 5 10/thousandths of an inch is that critical, however, lets look at the SAAMI specs. SAAMI standards for chambers (according to the 12 different books I have) are: .308 base .473", base of the web is .470", the shoulder is .454". The .30-06 base is .473", base of the web is .470", and the shoulder is .441". Even the taper is nearly the same up to the shoulder and then the angle is 20 degrees on the .308 and 17 on the 30-06. So it would indeed seem that the two cases are the same up to the shoulder of the .308.

Okay, so I have both cases here in front of me. Both fired from a Mossberg 100 ATR in the proper calibres. Both rifles purchased within 2 months of each other, both FL resized. The base of the web on the .308 is .467", the base of the web on the .30-06 is .465". Therefore both case bases and webs will fit in a SAAMI chamber.
The shoulder of the .308 is .448", the shoulder of the .30-06 is .439". Again, refer to the SAAMI standards above.
Since the .308 shoulder is truly bigger than the .30-06 shoulder then it really would make it quite impossible to chamber a .308 bullet in a .30-06 rifle. Perhaps you are correct.

..hold on there minute....

The .308 shoulder is 1.560" from the base of the case whereas the .30-06 shoulder is 1.748" from the base of the case. When I measure 1.560" from the base of the .30-06 case, (unfortunately I don't have a scaled drawing to work from at this moment so I must use the fired case) then I measure .448", the fired shoulder on the .308 was .448". If I took the time to draw this out and measured it, since the tapers are nearly the same, I am sure that it would prove similar in the SAAMI dimensions. So, I will have to conclude that a factory .308 round will quite easily chamber in a factory SAAMI chamber.
Since this has occurred more times than I like to see, I would have to say, again, that you are possibly incorrect in your conclusion that it is practically impossible to chamber a .308 round in a .30-06 case.

However, this is still not conclusive and I will carry out these measurements on new, factory rounds tomorrow and see if it can, indeed occur.
 
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I've done it, once, and not on purpose. I have 2 almost identical Tkka T3 rifles. one in 308, the other 30-06. Both have the same scope. The only diffrence is 2 inches barell length. I shot one round of 308 through the 06. The bolt was difficult to close, should have been my first clue. It shot no problem and hit the target, just a little off where I expected. The next round was also difficult to close the bolt, so I unloaded, checked out the rifle, a 06, and put it away for another day. No damage to the rifle or me but I learned a lesson.
 
Its easier to load a belted mag with the wrong ammo for sure. I saw what happened to a 300wby when a 338win mag was fired in it. Good stuff. Always make sure you have the right ammo. I would love a 270wby but haven't yet because my wife shoots 7mmwby. I worry about the ammo getting mixed up for both of us.
 
okay. 2 new unfired cartridges.

SAAMI ('06) .308 .30-06
Base= .473 .4655 .465
Web= .470 .464 .463
shoulder= .455(at 1.560" from base) .447 .445

I found a scaled drawing in "Ammo and Ballistics".
As we can see here, commercial chamber dimensions are quite generous. Commercial loadings, being that they must fit in all chambers are a fair bit smaller than the chambers. You can see that an unfired commercial .308 cartridge will quite easily chamber in a .30-06 rifle. It having dimensions often times up to 8 thousandths of an inch smaller than the chamber. And, if the extractor is strong enough, or your chamber is just a touch tighter, it will hold the case on the bolt face and it will then fire.
 
I Know someone who did it by accident as he owned and reloaded for both (I belive nearly identical rifles).......it scared the hell out of him and he immediately sold the 30-06 .

A shooter I dont' know was shooting 300 WM ammo in 300 WBY because the WBY ammo was too expensive.....I saw the fireformed brass and it looks a little funny with the radius shoulder so high up....Dont' think anything happened to him or the rifle....hopefully he's cured himself of that habit.
 
I have seen over the years some odd things at the range .One day at the next bench this guy said man my rifle is all over the map today .I walked over and said check you scope screws 130 grain 270 's should shoot better than . He said it's not my 270 this is a 30-06 I said well I see why the groups not so good this guy fired 3 270's out the 30-06 pipe .

Two years ago a friend boy shot a deer right in the neck at 40 yards with a 308 rifle but he was using a 300 savage ammo I have the csae I can send in a pic's it just streched it out
and was good shot .
 
actually, i've DONE it- on an brazilian mauser, and all you get is what looks like a rimless 45/70 case- not a great practise, but i won't have an 06 in my armoury for that reason- btw, you can also fit a 45 colt in a 44 mag cylinder- i DIDN'T TRY that one
and i had NO TROUBLE closing the bolt- just one heck of a BOOOM, a lot of smoke, and wtf???
 
t-star said:
actually, i've DONE it- on an brazilian mauser, and all you get is what looks like a rimless 45/70 case- not a great practise, but i won't have an 06 in my armoury for that reason- btw, you can also fit a 45 colt in a 44 mag cylinder- i DIDN'T TRY that one
and i had NO TROUBLE closing the bolt- just one heck of a BOOOM, a lot of smoke, and wtf???
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I just tied a .45 Colt in my .44 Ruger and its a no-go. The truncated cone bullet entered the chamber but the cartridge stopped on the case mouth, same for .45 Auto. Maybe you ran the .45 case through a .44 die.
 
My cousin did an unplanned experiment. He fired a 338 WM through a 30-378 Wby Mag. Stock blew apart. Bullet did go down the barrel. Bolt welded shut. Cut the barrel off to have a look and verified there was no bullet in the chamber, just deformed brass. He has since bought a new 30-378 and now labels and stores his ammo much better than just stacking the boxes together. 2000 dollar lesson there.
 
Boomer said:
I just tied a .45 Colt in my .44 Ruger and its a no-go. The truncated cone bullet entered the chamber but the cartridge stopped on the case mouth, same for .45 Auto. Maybe you ran the .45 case through a .44 die.
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to tell the truth , it was so long ago , it could have been a 45 CASING in a 44- or a reloaded round- i DO remember making a mental note NEVER TO CARRY THEM BOTH at the same time
 
Its all about directing pressure and can the chamber handle it, in some rifles its fine in others obvioulsly not.
 
I know of a fellow who shot 308 in his 30-06 Remington pump for years. Called it a 30 aught 8. Did not understand it was a 3006. His brass looked like 444 Marlin rimless.


I did a similar stunt, by accident, firing a 243 in a 6.5x55 in a pair of identical looking rifles.

Ezcess headspace is an issue if the bolt face is too far back, not if the shoulder is too far forward.
 
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