Blow up puzzler

D

Dennis Sorensen

Guest
I had a customer bring me a factory 700BDL Varmint .223. He had blown a reload and had removed it from the bolt face loosing the snap in extractor and lightly damaging the front edges of the bolt. The bolt lugs were considerably galled. I assumed he was loading too hot...

I removed the barrel, faced the recoil lug recesses true removing the galling... it took about 3 thou... I machined the bolt lugs by about 2 thou to clean them up. I set the barrel back so the headspace was minimum on a head space gauge. Installed a new Remington snap in extractor. You could feel the bolt close on the go gauge...

When the customer picked it up I disassembled the bolt and showed him how you could feel the go gauge at the end of the bolt closing... I told him it was important that he resize his cases so you can feel them when you close the bolt. It was explained and understood well...

He left happy and was eager to get back to testing...

Today he came back... another blown case and the bolt locked... and a sore eye from gas.. he was not wearing glasses..

I removed the bolt by gently tapping with a leather hammer,,, the case is welded to the bolt face...
223%20bolt%20face%202.jpg


I cut the case off for a better view. There is a little wedge of brass that flowed out in end clearance...
223%20bolt%20face%201.jpg


Here is a picture of the end of the barrel. You can see a brass smudge and some gas stain.
223%20barrel.jpg


Now comes the puzzle...
Load is 26.6 grains of BLC-2, Winchester brass with a CCI BR primer and a 55 grain V-Max. Sized cases were felt on bolt closing...17 rounds fired previous to this failure showed no signs of pressure and were shooting good groups, extraction was easy. Neck length and clearance are not an issue...
Fired brass looks like this...
223%20primer.jpg


Comments welcomed...​
 
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I hope that he uses some very good shooting glasses all the time now ......

What is the history of that batch of brass ? And did he try to anneal the case necks ?
Did he leave that round in the chamber for a while before shooting ? What velocity did it cronograph at ?
Pull down any remaing rounds to check if possible . I've seen a ring pushed to the case mouth by seating a soft bullet with too much neck tension and no champher on the case neck.


When you put it back together - this time test fire this rifle with new brass and a reasonable load of fresh IMR-4895 yourself .



Glenn:D
 
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How hard is the brass?

On the failed case?

Shoot well
Peter
 
Blownup

How is he weighing his powder charges?
Pulling bullets and weighing charges would be a good idea.
Having done P&V testing on .223 I know it's take a lot to get to the point he is at.
The round in a hot chamber and let soak could cause this. But it would have to be a hot! chamber and have plenty of soak time.
Is he using all the same cases? Case volume differences can wreak havoc.
 
All powder was weighed.. chamber was not hot - no soak time... some brass has been fired a couple of times, some is new... all from new bags of Winchester brass...case length and neck clearance are not an issue... no annealing done by him...

I think it is brass failure, faulty brass ... scary to think that but I can not rule that out ... I know I would not be using any more of it... I told him to buy some Lapua brass...

.... I have installed a used .222 bolt I had on hand ...
 
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Dennis Sorensen said:
I told him to buy some Lapua brass.
Click to expand...
May not help. Some of thier 6.5-284 and .308 brass lately has reportedly been soft.

Tell your customer to stop tipping the powder can as much in the meantime. The extra speed may not be worth the trouble. As you've seen - twice.
 
I would blame the brass,

Exactly the same happened to someone I know. Winchester new brass, 700/223/55Rem/26BL-C2. All charges weighted and bingo. A new bolt later, same load and it never happened again with any brass.

Shoot well
Peter
 
Blow Up

Dennis-One thing comes to mnd. Just a few years back, I was doing some load work. Accidentially, I left some test loads where the sun got to them. I was shooting a .243 with a 85g bullet and had my chrono. Not only did I break 4000 fps, the primer was completely fused to the case-absouletly no seam nor firing pin dimple. Scary, to say the least. Just a thought. V/R Greg
 
I vote for bad brass since other identical rounds seemed to be shooting OK. Hodgon shows that load about 4% under max, not really hot. About 3200 fps with the 55 gr bullet. Looks like a very local failure right at the extractor groove, not the "usual" split up the side.
 
Did he start with a new, sealed, can of Blc-2? Or did he buy a part of a can at a gun or yard sale?? Could be some mixed powder not throughly mixed!
 
quickload software puts that at about 60kpsi...or a 5% overload from saami specs.
17 in a row...seems there would be some latent heat.....

and yes the first primer you show says he aint at the pressure.....

so something aint right.......

and 26.6 is 103% case volume. so compressed ?
is it blc2 or milsurplus blc2 ??

mike

mike in co
 
blow ups

Hi Dennis,

I remember several years ago reading an article on blow ups.They were happening for no apparent reason. The article focused not on the action or loads but rather the barrel.

Guys would be shooting normal loads and poof just like what you have,blow up --- repair ,shoot shoot blow -up.What the ----.

They started to look at the condition of the barrel and what the found was it had shot lots and the bore had become "alligatored".The only conclusion they could find was the bullet would jump from the cart. and into the bore where it would be grabbed by the roughness of the bore and the pressures sky rocket.

I feel they are right is I can confirm this on several M16 and Ar 15 that came in because of blow ups.NO reason ,factory ammo.Upon inspection of everyone with a borescope one could see the bore was in poor conditon.

If you can check out this guys bore

chris
 
Fresh loads not in the sun, sealed cans of factory BLC-2, and the barrel looks very good...

More and more I am thinking a couple of very soft brass...
 
Bolt nose to counter bore clearance?

Dennis,

You left out the most important factor in that type of blow-up.............what is the front bolt nose to counter bore clearance?

The first picture looks like it must be over spec., the brass looks like it formed a huge bulge in the clearance area. I like a .005-.007 gap, nothing over .010.

Also check to see if the bolt face has been machined back too far, which in turn would move the solid head of the case too deep and expose the thinner portion of the case wall to the bolt nose to counter bore gap.

Something is wrong in that general area and should be pretty easy to find once you get all the dimensions sorted out.................Don
 
There are so many varriables to handloads...its hard to say.

Does look like a brass problem or exxesive presure ?

Good luck
 
Question

Dennis good morning. It looks like the fellow was lucky to be shooting a Remington a catastrophic failure like that and twice could have been a disaster in many other rifles. I'll bet his underwear also took a hit.

Have you measured the length of the tenon from the lug to the tenon face.

Could the barrel tenon have been cut short and the chamber shallow not giving the case the necessary support?

How many rounds have been successfully fired prior in this rifle. That could identify if it is a brass problem or a rifle problem.

Is this a factory barreled action or a rebarreled action? If this factory barreled action and ther is a problem Remeington needs to be notified. If this was a rebarrel the smith needs to be notified and his technique needs to be double checked.

Rustystud
 
Rustystud said:
Dennis good morning. It looks like the fellow was lucky to be shooting a Remington a catastrophic failure like that and twice could have been a disaster in many other rifles. I'll bet his underwear also took a hit.

Have you measured the length of the tenon from the lug to the tenon face.

Could the barrel tenon have been cut short and the chamber shallow not giving the case the necessary support?

How many rounds have been successfully fired prior in this rifle. That could identify if it is a brass problem or a rifle problem.

Is this a factory barreled action or a rebarreled action? If this factory barreled action and ther is a problem Remeington needs to be notified. If this was a rebarrel the smith needs to be notified and his technique needs to be double checked.

Rustystud
Click to expand...

That is what I told him... any other action would have seen way more damage. He was lucky this happened with a 700.

The end clearance was normal when the first case blew. It was even tighter when the second case blew. It was a factory rifle until I set the barrel back after fixing it. He has fired probably 300 rounds through it before it blew the first case... and then 17 rounds before it blew the second case. No signs of excessive pressure before the blow ups... he has a few hundred of new Winchester brass and about 8 pounds of BLC-2 in the original containers.
 
A decent pair of safety glasses is only about $10. Surgery to remove what is left of a damaged eye is over $20,000 and a glass eye is over $700, walking into doors and bumping into people for the rest of your life is embarrassing.

Please, please ask this fellowto wear safety glasses and each of you wear them as well.

Like I always say, it's all fun and games until Larry gets his eye put out.
 
That sure looks like the web of the case is not in the barrel far enough. The head space gague may not be telling the whole story cuse of where the barrel champher is - it may be boarder line. Seen this with a drop port configuration.

JR
 
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