Winchester Primer Failure

Hmmm. Load data appears to vary by manual. The Lyman 49th edition lists 44.0gr of IMR4320 as max for a 150gr SP projectile using Federal 210 primers. The Hornady 8th edition lists 40.7gr of IMR 4320 as max for a 150gr SP projectile using Winchester LR primers. The primers may be the key element as the WLR raise the pressure slightly higher than the Federal 210. At least according to Lyman's data on various primers. The combination of hot powder load and slightly hotter WLR primer may be contributing factors.

Just reading through the data and trying to put 2 and 2 together. I'm new at this too.
 
Cleftwynd said:
Some rifles will hit WAY higher pressures sooner than the next in the same chambering, even by the same maker in the same model. The book maximums are NOT an absolute, that is why you start low and work up. It is VERY possible you are over pressure with an above published maximum load. And comparing 4320 to 4895 just by published burn rates is like comparing apples and rain drops, it can not be done. Everything from case capacity to primer to seating depth to charge volume to.... well that throws all assumptions out the window, don't try and use 4895 data and assume that you would be safe with 4320 just because it is listed as a slower burn rate!

More often than not I reach max pressures sooner than expected due to tight chambers, short or no freebore/throat, etc...
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I understand what you're saying, but I'm sure this is an issue with the primers. I've loaded 42.5g of 4320 behind a 174 grain bullet using CCI primers with no issues. 40 grains behind the same bullet is a problem for these winchester primers (different load for different rifle, same primer problem)

Other than the odd hole blown through the primers, there have been no signs of over-pressure. 303 British is not a high pressure round to begin with. I wonder how these primers would react in something like a .308?
 
I have experienced this with WLR primers. Blow out is small pinhole on the outer corner of the cup, not even near the firing pin dent. Made a nice little pit mark in the bolt face.

I think I kept the primer...
 
Not my pic (mine was in a boltgun) but identical result:

MPrimerIssue.jpg
 
I had some winchester primers do this with mild loads in 7mm rem mag. i was 2 grains off max loads in any book
and blew out 5 primers over many diffrent days. Switched to cci had no problems since.
 
Ive got a few casings/primers that look just like that and 2 damaged bolt faces too. As i said above 4 grains below my cci primer load. Not very happy.
 
I've just experienced the same problem with a WLR primer blowing out the edge. I have contacted Winchester and they are replacing them. My lot # was DKL787G. I filled out the problem form on Winchester's website and they contacted me within a week. Thumbs up for Winchester.
 
'Boo said:
The fact you are well over the maximum 40.7 grains the Hornady lists for that combo might well have something to do with your blowing primers.
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Lyman reloading handbook, 49th Edition, page 249. Max load 44gr 4320
Sierra Rifle Reloading Manual, 3rd Edition, page 387. Max load 44.9gr 4320

For a couple of quick references. That's why it's good to use more than one.
 
I've never had a WLR fail to fire or blow out even when I was using them to push my 7mm mag. I didn't push it as far as some guys here do.

I'm still using the old silver ones though.
 
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