Lapua 308 case failure your thoughts

[manitou210]

Club Shooter was having troubles trying to eject shell from his Barnard F class .308 win
He was able to get bolt open but empty case was still in gun and extractor fell off he found it in grass.
He then tried to get empty case out by dropping a heavy piece of metal about 10 to 12 " long down bore after 3 or 4 times he then actually threw the piece down barrel and casing came out.
The case had ruptured in two places near base, the primer did not show excessive pressure he had a Lapua box The primers looked fine for pressure of 18 or so fired The Head stamp was .308 win Lapua on all 18
The case that had ruptured was marked 7.62 by 51 Lapua
I measured each case 308 win Lapua 2.006"
The 7.62 x51 measured 2.013"
both cases weighed the same 172.2 grains.
The loads were with IMR 4064 at 45.9 grains according to
new member bullets were Sierra 155 gr 2155
range officer came over and looked at brass, and immediately told shooter to pack-up no more shooting.

You can see the ejector pull a piece of brass off rim
my thoughts on this the case had corroding as you see on photo shooter claims there was none on case corrosion was on inside case ??






9 Attachments

 

[dkhunt14]

Looks like the brass had a bad spot. Don't know why the head stamp is different. I would contact Lapua. Matt

 

[riflewoman]

What you have is an “k” split. This is how these defects are categorized and is based on a location classification captioning. See here. http://everyspec.com/MIL-STD/MIL-STD-0500-0699/download.php?spec=MIL-STD-636.019493.PDF It is not outstandingly hazardous, but gas leakage can occur if the breeching of the gun is poorly designed.

The different headstamp indicated that this collection of brass comes from two lots merged together. Whether this happened after the brass left the factory or before is unknown but far more likely the former. I’d retire the whole lot at this point.

This failure indicates that brass has a definitive life other than primer pocket enlargement and neck splits.

 

[JimSC]

What you have is an “k” split. This is how these defects are categorized and is based on a location classification captioning. See here. http://everyspec.com/MIL-STD/MIL-STD-0500-0699/download.php?spec=MIL-STD-636.019493.PDF It is not outstandingly hazardous, but gas leakage can occur if the breeching of the gun is poorly designed.

The different headstamp indicated that this collection of brass comes from two lots merged together. Whether this happened after the brass left the factory or before is unknown but far more likely the former. I’d retire the whole lot at this point.

This failure indicates that brass has a definitive life other than primer pocket enlargement and neck splits.

I had one of those occur last year, never knew what it was called but I replaced that batch of cases just of of instinct. I did not notice anything unusual at the range but only noticed when I cleaned the cases. Thanks for that link

 

[Curmudgeon]

Slightly confused. Extractor "fell off", did shooter do the reloading?, "threw a piece of metal down the barrel", don't blame the range officer for telling the shooter to go home. Not a very good explanation of events. Not a very smart way to approach f class.