My first Lapua case head separation

[kelbro]

Post an enlarged pic of the base of case

This angle?

 

[kelbro]

Another inspection yielded 5 cases with a 'ring' at the same point the other case separated.

I ran my borescope through some good cases and then through those with the rings. On those with the ring, I see a brass colored halo inside with the borescope. My guess is that this brass halo is impending doom.

Here are some images...

 

[M-61]

Turns out that it was bumping the shoulder something like .005-.006 each firing (IE WAY too much bump). Should have known due to the frequent need for trimming the cases.

I always am concerned about where reloaders think that brass is coming from.

 

[Tesoro]

This angle?

View attachment 1760813

Well you had one shot with a very hot load - enough to squash half the A. You have weirdest looking brass I have seen. Pic one looks like a belted magnum but in the wrong place. The shoulder-neck junctions in next pics very strange and then you have boresite pic where you found a sperm inside a case.
Time to back peddle a bit.

 

[ELR LVR]

Pic one looks like a belted magnum but in the wrong place.

That's what I was seeing also
it does look like a belted magnum
it's an optical illusion, the split just ahead of the wear pattern makes it look like a belt
---
Kelbro, did you check your barrel tightness?
Is it possible it came loose slightly? (thereby increasing headspace)
Lugs worn down on the bolt? Newly lapped lugs?
Anything like that?

 

[M-61]

Lugs worn down on the bolt?

I never thought of that.
I didn’t see what he was shooting.
Stainless steel loves gall. I always wipe my lugs with wheel bearing grease. Just a light wipe. Shear factor is the reason for my choice. I think from my observations it is something that is neglected.

 

[kelbro]

As far as the lugs and headspace, I am not measuring more than .001 lengthening of the case at the shoulder.

The 'belt' look is just from the camera angle. That band measures exactly the same as those that have the ring. The other pictures show that. That crack looks like a glass cut.

I looked at the receipt in the box that these came from. It was a batch of 200 that I have cycled through off and on since 2008.

Yes, I have loaded some of them a little hot once or twice doing load development but I don't run hot loads. There are about 40 pieces that I have retired due to primer pocket expansion.

Thinking back, there may have been some sizings back before I worried about shoulder bumps that set the shoulders back more than was ideal.

I've gotten my money's worth out of this brass. I just need to make sure that I do better inspections going forward, despite adopting better reloading practices.

 

[209jones]

Primer pockets may possibly be a sign that the loads are maybe a bit hotter than you think they are, or may just be that batch of brass, not hot enough to show anything obvious, but over time they wreck the brass. You say you got 12-15 or maybe a few more out of these, any idea what you got out of the ones with the pocket issue, or were they even traceable to the hot loads for sure?

 

[DShortt]

The images in post #22 show a bright, shiny ring. Which means that just happened on the last firing.

Just sayin'.

 

[Straightshooter1]

Another inspection yielded 5 cases with a 'ring' at the same point the other case separated.

I ran my borescope through some good cases and then through those with the rings. On those with the ring, I see a brass colored halo inside with the borescope. My guess is that this brass halo is impending doom.

Here are some images...

View attachment 1760838View attachment 1760839View attachment 1760840

Those are certain signs of head separation about to occur for sure. And any of that batch that isn't quite showing any of that, they'll mostly likely be showing that on the next firing. Therefore, I'd say it's time to dump that batch and get some new brass.

 

[kelbro]

Primer pockets may possibly be a sign that the loads are maybe a bit hotter than you think they are, or may just be that batch of brass, not hot enough to show anything obvious, but over time they wreck the brass. You say you got 12-15 or maybe a few more out of these, any idea what you got out of the ones with the pocket issue, or were they even traceable to the hot loads for sure?

Yes, the loose primer pockets were most likely from the warmer loads. It was gradual as I was just at the edge of max pressure for several batches.

The images in post #22 show a bright, shiny ring. Which means that just happened on the last firing.

Just sayin'.

I guess it had just reached end of life on the last load because this last batch was about 2 full grains less of H4895 than the previous 12-15 loads. Due to the primer pockets loosening, I have been trying to find the next lower node (I did find it!).

Those are certain signs of head separation about to occur for sure. And any of that batch that isn't quite showing any of that, they'll mostly likely be showing that on the next firing. Therefore, I'd say it's time to dump that batch and get some new brass.

Agreed. I really don't want to remove a broken case from my action. I've done that only once on a die and it was not fun.

 

[Paddyd]

One way to mitigate this is to fireform correctly for the first 2 firings. What I mean is since new brass is always undersize, you need to load bullets used for fire forming long enough to at least touch the lands if not actually in the lands. This makes sure the bolt face and case head remain in contact with each other when the firing pin hits. This keeps all initial stretch to the shoulder area and not in front of the web area where yours are separating at. Also, i only neck size for the first 2 or 3 loadings to get a good complete foring of the case . After that, only set the shoulder back " just enough" to allow easy chambering. If hunting, Id go 1.5 to .002" set back. For a bench rifle, only about half to 1 thousandth . Do that and you should easily get 20 firings from premium brass as long as you arent pushing pressure to max.

 

[kelbro]

One way to mitigate this is to fireform correctly for the first 2 firings. What I mean is since new brass is always undersize, you need to load bullets used for fire forming long enough to at least touch the lands if not actually in the lands. This makes sure the bolt face and case head remain in contact with each other when the firing pin hits. This keeps all initial stretch to the shoulder area and not in front of the web area where yours are separating at. Also, i only neck size for the first 2 or 3 loadings to get a good complete foring of the case . After that, only set the shoulder back " just enough" to allow easy chambering. If hunting, Id go 1.5 to .002" set back. For a bench rifle, only about half to 1 thousandth . Do that and you should easily get 20 firings from premium brass as long as you arent pushing pressure to max.

Great advice. Thanks for adding that.