Results of a severe overload in a 6mm BR (Norma)

W

WisFinnlander

Guest
Just had to show what happened a couple of weeks ago to my friend, over 54 years of reloading experience,one mistake was costly. The pictures below will show the damage. He had over 300 rounds through the rifle so it was not new. First shot of the day had a puff of smoke out of the action and around the striker, luckily that was all. At home he managed to unlock the action and break off the bolt handle, a rod brought the bolt back till the expanded nose wouldn't go through the action.
After taking off the barrel it was hard to believe how bad it was damaged. The case was totally blown in two at the bolt nose, head like forged into the bolt. Inside the counterbore is a brass wash. The bolt did drive out of the receiver quite easily. Bolt nose is expanded to counterbore size (.715),the locking lugs are also expanded(.012) larger than there original diameter.The lug recess in the receiver show the imprint of the bolt, The lower one is deeper by several thou than the upper.The cartridge case is still in the chamber, just haven't had time to get it out (prairie dog week is coming).A piece of brass on the bolt nose showed it was set up with about .010 tick tock, I did not like the chamfer on the chamber.
The load was 5 grains more of Rl 7 than he planned on loading with 68 gr bullets. In this case the three rings of steel did their job.
Dale
 

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That'll make me double check my scale settings next time. Ouch!
 
WOW ! ! ! Im glad you friend wasnt hurt, that could have turned real ugly. R.K.
 
He is lucky it was the original 700 extractor system... and the chamber chamfer looks way too large.
 
Dennis Sorensen said:
He is lucky it was the original 700 extractor system... and the chamber chamfer looks way too large.
Click to expand...

Dennis, I think what you are seeing is the seperated case remaining in the chamber and not an exagerated chamber chamfer............Don
 
Now for the big question.............are the action body and bolt ruined?

Even if the action/bolt lug areas magnafluxed/xrayed showing no signs of cracks, do you still trust the integrety of metal that has moved enough to show considerable measurable dimension changes?

Glad I dont have to make the call on that action. Yeah, some will say if there is any doubt at all throw the whole thing out, no sense in chancing injury over a piece of hardware. Others will probably say true it up and proof load test it behind a barrier, if it holds up it is good to go.

Wonder how you de-commission an action and report it to the ATF.....................have not seen that one discussed on this forum.......Don
 
How many grains of Rel7 can a 6br case hold? Enough to move that much action metal around without a bore obstruction?

One of the nice things about these smaller cases is that it is usually difficult to overload them, double charge them, unless using pistol/shotgun powder in a rifle case..............Don
 
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I can make a call on that action, IMO the answer here is easy.... that receiver is SCRAP!!

The cost to test it exceeds the cost of a new action, and then you've got to FIX it.

Thank God for the "Three Rings Of Steel!"

al
 
Don said:
How many grains of Rel7 can a 6br case hold? Enough to move that much action metal around without a bore obstruction?

One of the nice things about these smaller cases is that it is usually difficult to overload them, double charge them, unless using pistol/shotgun powder in a rifle case..............Don
Click to expand...
Don, I'm kind of wondering in the same direction. Why use Rl-7 in a 6BR?

100% load density for the above, according to QuickLOAD, is about 33 grains, or about 96,000 pressure, not a good choice, IMO.
 
Remington actions are evenly heat treated throughout. They are not spot treated nor surface hardened. I have never heard of any 700 series actions cracking - ever... I have never seen one actually blown up either.

If it was my action I would have no qualms about truing it and using it again.
 
Dennis Sorensen said:
Remington actions are evenly heat treated throughout. They are not spot treated nor surface hardened. I have never heard of any 700 series actions cracking - ever... I have never seen one actually blown up either.

If it was my action I would have no qualms about truing it and using it again.
Click to expand...


Dennis, look again at the setback imprint on the lug seat.

Would you really just cut that off and proceed?

al
 
alinwa said:
Dennis, look again at the setback imprint on the lug seat.

Would you really just cut that off and proceed?

al
Click to expand...

Maybe it is worse than it looks... if 5 thou would clean it up the worst would be what was lost in the initial extraction camming ... ?

You could always send it back to Remington for a new barrel. :D
 
Dennis Sorensen said:
Maybe it is worse than it looks... if 5 thou would clean it up the worst would be what was lost in the initial extraction camming ... ?

You could always send it back to Remington for a new barrel. :D
Click to expand...

Yeahh very funny!

Seriously though, I can't picture that sort of stamp into hardened steel not being accompanied by micro-cracking.

al
 
I really doubt there is any micro-cracking. 700's are not very hard but they are tough and pliable. I think it takes greater hardness to micro-crack.

It would be a great action to do a test on... fit another barrel and another bolt to the correct headspace and do the same thing... keep on doing it until the action fails...
 
Dennis Sorensen said:
I really doubt there is any micro-cracking. 700's are not very hard but they are tough and pliable. I think it takes greater hardness to micro-crack.

It would be a great action to do a test on... fit another barrel and another bolt to the correct headspace and do the same thing... keep on doing it until the action fails...
Click to expand...

Thought I remembered reading somewhere (Otteson perhaps) that the rated yield strength of the Rem. 700 action material was in the neighborhood of 140k-150k psi, strange that this overload nearly reached these levels.........Don
 
Just got back from up North and had a chance to look at the replies on the overload. The barrel is not ringed or bulged so it was not a bore obstruction. I have no reason to doubt my friend when he said it was loaded with Rl 7. The bolt is going to a hunters ed instuctor for display. The action has not been trued up yet (prairie dog week stars Monday) but it appears .003 to .005 will clean it up. Dennis do you think if it does clean up we could use it on a 222 sized case? Just asking ,if not maybe we will do the destructive test thing, big problem is I hate to ruin another bolt. Getting back to the barrel, that is all chamfer showing in the picture. Tomorrow I'll pull the case out and see what is left where it was blown off.
Dale
 
back-up scale

About a year ago, I wound up with my digital scale next to my beam scale. Not out of forethought, but there have been a couple of occasions I was glad it was there. In setting the beam scale, I have missed it by 1 mark, which is 5 grains, twice. Once it was 5 grs too high, and just last week it was 5 too low. It now has a permanent home next to the beam just to catch any possible errors, and so far it has.

5 grs too much in a .223 would have overflowed the case and been pretty obvious, but 5 too low could have went unnoticed and more than likely would have had similiar results being that underloaded.
 
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