Lapua 308 brass with annealing on case head

Q

qball16

Inactive
Hello all.

First post. I have found 14 new cases in my latest box of Lapua brass that show signs of annealing on the case heads. I have attached a picture. Has anyone ever seen this? Would you use them? I'm concerned that the primer pockets will stretch out on first firing.

Thanks,

Scott
 

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It's brand new. They have the rainbow colored heat marks on about a quarter of the head and up the case a bit. Like I said, it was on 14 of the 100 cases in the box. I have used another box from this lot and none of the cases had this coloring.
 
I'd use them. Oxidation like that can come from solvents or other sources.

Easiest thing to do to be sure is mark those 14 brass and use them for your load workup. If they have soft primer release after the load work up, you'll know right away and can cull the cases. I expect that they'll be fine though, it doesn't look like anything I'd be worried about in new brass. Keep an eye on it and let us know how it works out for you.

Jimo
 
Not sure what 1stmar is referring to as a possible extractor mark. Is something covering a section of the rim near the 7:00 position? But probably that answer would not help answering the rainbow coloring question. Apparently the inside of the questionable cases and primer pockets are normally bright with the appropriate shine? So far I would think the cases are good. Let's hear what others have to offer on the unusual coloring.
 
The object at the 7 O'clock position is another case in the tray. I had to severely crop the picture to try to get under the file size limit. The coloring on these 14 case heads looks exactly like the intentional annealing that that Lapua performs to the case neck on their new cases.

Scott
 
OP. I have purchased and used many Lapua brass cases, and none of them had the tell tale "blue" coloration on the case heads which they have on the shoulders and necks. Perhaps call them at Lapua and ask them what they think? Personally, I would be reluctant to use those specific cases.
 
Just to be clear, the black color is only oxidation. It's the same stuff that happens to statues and cannons. All brass turns black eventually if exposed to oxygen. It isn't proof of heat.

We associate that color with annealing because annealing creates a predictable oxidation pattern on polished brass. You can duplicate the annealing pattern around the neck/shoulder area using chemicals to create surface oxidation.

The reason why I don't think that the oxidation on the case head is from an annealing process is that it is highly localized in an area where the brass is very thick relative to the neck/shoulder area. If it were caused by a heat source it would have been very intense and very short lived or the entire case head would have the oxidation.

On the other hand, the brass coming in contact with cardboard or other paper product that was bleached could accelerate the oxidation process.

But if someone is really worried, tossing 14 cases isn't the end of the world by any means.

Jimro
 
I know it's a horrible photo. The color does go to the bottom of the lettering. The coloring goes from about the 2 O'clock position to the 5 O'clock position. The bottoms of the letters "LAP" are discolored. I'm going to contact Lapua. I'll let everyone know what they say. Thanks for the input everyone.
 
qball16

I have been reloading with Lapua brass for my last 20,000 rifle rounds with all of my favorite rifles and load Lapua brass exclusively with both of my .308 target rifles. I have never noticed any annealing marks on the cartridge case heads. I inspect the cases carefully every time I reload, including the first time I use them. Generally, Lapua brass and Norma/Nosler brass are the best quality controlled new brass I have used.

That said, Lapua brass generally gives me more than 20 reloads per case with my .308 brass. The primer pockets generally wear out before the necks but at over 20 reloads or so after that many full resizings, a few of the necks begin to split. Then I replace the entire 100 cases. Normally, the primer pockets begin to get looser than I like them to be before the necks begin to split. Lapua brass has always produced the highest number of reloads before neck splitting. I keep meticulous records and have found that Federal and Winchester give me 8 to 10 reloads before case necks start to split, Norma/Nosler give me about 16 but Lapua gives me at least 20. That and very consistent results have made Lapua the brass of choice for me.

Annealing hardens the brass in the necks and it helps to maintain consistent neck tension. I'm not sure why you would be so concerned about extra hardness in the case head when it is thicker than the neck and supported by the bolt and chamber so it won't tend be stressed as much as the neck.
 
I was under the impression that annealing softens the brass and fights work hardening. That is why you do it only to the necks and upper body, where extra flexibility is desirable for resizing and expansion on firing.
 
You are correct qball.

That is a little oxidation discoloring. If it went through the annealing process upside down you would expect it to be more toward the case neck and even all the way around.
 
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