11-24-2021, 11:01 PM
tdbru Wrote:I'm tending to agree with LRRPF52. the primer is not flattened nor cratered. extractor not blown off, bolt lugs all there. and the case head came off the bolt face pretty easy. also notice no case head material flowing into the ejector hole. Just one of those rare pieces of bad brass it appears. Of course the suggestions to get the headspace checked would be prudent as well. Even the lettering on the headstamp has not been squashed or obliterated. no black ring around the primer. I doubt the primer pocket has been enlarged. All the typical signs of an overpressure round are absent save the case head separation. However i've had case head separations on some of my reloads where i was going to get the very last load out of the case. Probably around load 25 or so. So there are case head separations without overpressure, but the brass usually tells you it's about to give up before it does by showing a bright ring around the case just above the web of the case. Another thought was that this case got caught in the annealing machine at the factory and was annealed all the way through, not just at the neck. However OP said 1x fired so that over annealed case hypothesis may not hold water. Anyway I too think it wasn't over pressure but just a bad piece of brass.
regards,
tdbru
Kind of, this one is odd. Because there does appear to be extrusion or deformation at the extractor area, and possibly at the ejector area. I thought so at second glance at least. but at 3rd glance, the primer isn't as flattened and the lettering isn't as flattened as typical with an overpressure. So some signs to me say overpressure, but some signs say... maybe not.
It is curious that it's a Lapua casing. That's generally viewed as the standard of high QC above all others, and I've not seen this sort of failure anywhere else yet.