I have been working on loads for my 300 Savage 99. I have probably gone through about 70 rounds using WW LRP. I have had two cases where the primer blew a small pinhole in the primer edge. The holes were located at the radius edge of the primer where it enters the case. The case shows no damage. The hole is through the primer cup and you need a magnifying glass to see it clearly.
Anybody seen this?

I have seen it with some Berdan primed military brass. I would take some good pics and send to Winchester along with the type and lot #.

Have you inspected the primers in your loaded cartridges before firing for any abnormalities? I would also check your priming ram to ensure there is nothing on it's surface that could mark the primers when seating.

I'd almost bet that the primer cups have defective metallurgy.

I also think you'll find a flame-cut divot, or two, in the boltface.

I experienced that same damage, years ago, with some Fed 205M primers.

Hope this helps.

Kevin

This problem with Winchester primers has also been discussed on some other forums recently. No definitive answer as to why it is happening. The Winchester customer rep did respond to people who complained.
WARNING Defective Winchester 41 primers on the shelves

wlr bad lot number

So it is a known problem. I think I will move to CCI brand for my load work. Thanks for the info guys.

Years ago I had a fired Winchester large rifle magnum that appeared to have a seam down the whole side of the cup. The fire did cut the bolt face. To me it looked like the cup was cut/punched too close to the edge of the sheet. Instead of a solid cup it had a seam! I sent pictures to Winchester but they never responded. I think I still have the pictures.

Its a blow out and not a problem, toss the case and changing primers won't change a thing except maybe Ill buy your old pimers??

I have most of a case of WW large pistol primers that do the same thing. I use them mostly in my .45 acp where it doesn't seem to cause any problems.
C.G.B.

Yep. This issue has been discussed quite a bit over the last 15(?) or so years. Let me guess - the primers in question are the brass colored WLRs that show green on the inside? Probably manufactured in the mid to late 2000s. With enough searching you can even find a list of affected lot numbers. If I were you I would just stop using those primers and move on. At a minimum, make sure to wear safety glasses when using them. You probably don't want a jet of hot gas blowing back into your face through the bolt firing pin hole (depending on rifle design of course). I could usually tell a failure when I pulled the trigger because of the smell in my face as the gas escaped and was vented down through the magazine box.