Case head separation?

[Bob Nelson 35Whelen]

Hey guys this is the first time I've ever seen anything like this and this is NOT a reload, this is brand new factory ammo. This was the last box off PPU ammo I've had for about a year now, I've shot at least 6 or 8 boxes of this stuff with no problems but these three all sounded and felt weird when I pulled the trigger and there was another round that didn't go off at all. No i didn't try to shoot it again. I opened up a box of Federal after these and had no issues so there's nothing wrong with my rifle, this is my Model 70 Safari Express and she shoots great. So what caused this and should I trash the whole box of brass just in case? These are 3 different cases but one case split in two places almost all the way around so I took a couple extra photos.

@Axle2010
Personally I wouldn't use anymore out of that box.
I would pull a loaded round and check for incipient seperation but more likely just a bad batch of brass. I can understand this in reloaded cases but not brand new.
Bob

 

[Axle2010]

@Axle2010
Personally I wouldn't use anymore out of that box.
I would pull a loaded round and check for incipient seperation but more likely just a bad batch of brass. I can understand this in reloaded cases but not brand new.
Bob

Fortunately the one that didnt go off at all was the last one in the box so there's no more to ahoot anyway. I'm going to try and get in touch with PPU tomorrow and see what they say about it.

 

[Grumpy gumpy]

Fortunately the one that didnt go off at all was the last one in the box so there's no more to ahoot anyway. I'm going to try and get in touch with PPU tomorrow and see what they say about it.

If they play silly games with you, show them the picture I posted and I’ll try to find the picture of the 375H&H case that did the same.
Gumpy

 

[Bob Nelson 35Whelen]

Your description of the sound of a muzzleloader with slow ignition is the round doing exactly that. The primer pops but there’s a delay of the charge going off. The primer pop can move the bullet forward to meet the rifling then the main Charge ignites. This is dangerous because it can behave as though it has a bore obstruction causing excessive pressure. It is not an uncommon thing with old surplus military ammo. There’s nothing wrong with your rifle it’s the rounds. Hence the one that wouldn’t fire at all. Why these did this is pure speculation but what they did from your description isn’t in my opinion.

@Vintageguy
The scenario you describe where the powder only party ignited and the bullet gets jammed in the lands then the rest of the powder ignited is call Secondary Explosion Effect (SEE) for short.
This scenario can cause the rifle to disintegrate very quickly.
This has been tried to be replicated in controlled experiments but has had limited success.
It is something no-one wants to see happen.
Seems to be more common in the 243 and 22-250 in rifles with eroded throats. My gunsmith has seen this in a couple of tikka 243s, not pretty.
Bob