[Unclenick]

Bart,

One of the things I remember from Kevin Thomas's articles in P.S. in '98 or '99, IIRC, is he mentioned that Sierra had a set aside lot of 168's that had proved exceptionally accurate that they used as accuracy reference bullets. He was using them in the tests he wrote up for the magazine. It may be any bragging groups you saw were fired with these. It may be they've also set aside extra accurate examples of the other MatchKing weights, but I don't know.

The only way I can think of to verify the flat base theory via Sierra would be to look at accuracy standard deviations from different lots, including rejects. Assuming the flat base is easier to manufacture accurately, I'd expect to see lower SD's with correspondingly fewer rejected lots. Once you get past the rejects it's harder to tell, as the rejection criteria, assuming it's equal, biases them all toward sameness.

And the stats would cover only the bullet half of the equation, as Thomas disposed of test barrels as soon as any evidence of them being shot out appeared. I assume that's S.O.P. there, and not just for his tests. So, to the extent using a flat base confers any better immunity to minor crown imperfections and the like, you wouldn't see it there. That would have to tried with an intentionally damaged crown for hard evidence.