Over pressure?

[Benchrest Braxton]

it seems obvious that this is an issue of cup defects, whether they are even overpressure is kind of irrelevant, because I have seen some severely overpressure rounds and I have never seen pinholes created from such.

 

[fkimble@charter.net]

I had a lot of Rem 7 1/2 primers do the same thing .223 CLE spacegun barrel. R15 24.0 grs, Sierra 80 gr.Win brass. Ran out of Wolfs for 600 and went to the 7 1/2s. 1 or 3 every 20 at 600. Kept backing powder down .2. Didn't help. Research found a mention of it many years ago in Rem 7 1/2s! My Rems had been on my shelf for "same" many years. Cause was Rem went from 3 legged anvils to 2 legs, cup supposedly the same. Seems they would pierce in the curve where the cup was stressed a little during manufacture. The 2 legs directed the pressure to a smaller area of the cup radius than the 3 legs. Rem went back to 3 legs and all was good. Wonder if Win did same thing or maybe a batch of just thinner stock or manufacturing snafu. I went to 450s and all was well. just for grins I loaded a couple with 400s. 450s still had nice rounded primers. The 400 were noticably a littler flatter but nothing to get worried about. Ended up using the 7 1/2s for my 100 yd practice ammo. Much lighter load.

Frank

 

[Bill K]

Thought the #41 primer was put out by CCI. Did Winchester make them also ?