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Old November 23, 2012, 10:40 AM   #52
Bart B.
Senior Member
Join Date: February 15, 2009
Posts: 6,318
Old Roper, I was one of the Palma Team members that developed the load in early 1991 those Winchester cases were made for Sierra's prototype 155's they sent us to test with. We developed loads to test with cases weighing between 165 and 170 grains. I weighed about 50 random samples of the 92 PALMA ones I got from the first match that ammo was used in the summer of 1991. Weight spread was 1.5 grains; excellent by any means. Mid told me back in the early 1970's that a 1% spread in case weight's good enough. That's the only case "prep" he's ever done; no flash hole or pocket reaming. Sometimes he would turn necks if they had more than a .001" spread in wall thickness.

I bunked with Bob Jensen in South Africa in the late 1990's for their Nationals and we talked one night about those 92 PALMA headstamped cases. The Western Cartridge Company plant in Illinois had to try 3 or 4 sets of case forming dies for the coin, cup, draw, head and trim processes to make them from cartridge brass sheets. Those cases were a little better than the great WCC58 and WCC60 match cases made there for the US Olympic Free Rifle Team in those years. Having many hundreds of each and weighed some of them, they were 1.8 to 2.1 grains for spread.

In a phone chat with WCC's production engineer in 1991 about those cases, he said that someone had asked about using those old dies they still have stored away for the 92 PALMA run. But WCC denied as the WCC58's averaged 150 grains and the WCC60 156; too thin for safety in the 1990's 'cause so many people loaded ammo way too hot. Which is why the 92 PALMA ones averaged about 169 grains.

That ammo shot about 1/2 MOA at worst in several rifles from around the world in the first match it was used in; 1991 Rocky Mountain Palma Matches at the NRA range at the Whittington Center, Raton, NM. A year later at the 1992 World Palma Matches held there, top long range competitors from all over said it was the most accurate batch of ammo they had ever shot. At a dinner on night during that event with Bob, Mid and others, one conversation was about how so many folks waste lots of time measuring stuff that doesn't matter trying to get the best accuracy. Case weight spread of 1% is good enough.

Last edited by Bart B.; November 24, 2012 at 09:11 AM.
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