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Bart -- Buhay is a friend of mine, and you can call him if you like...
[/ QUOTE ]Thanks, but I finally found Buhay's info on a web site.
Question; are the measurements made from bore diameter datum points at both ends of the bullet? Seems to me that's the best way as it's betwen those two points the rifling engraves the bullet down to. And a .001-inch or so difference between the different bore diameters for a given caliber won't matter much.
I'm gonna have to measure some of my Sierra standards and see what their spread is.
David Tubb gets the ogive checker he sells from John Buhay in PA and then markets it under his name. Go to page 19 of the RW Hart catalog and you will see it there listed for $125. David also gets the metplat trimmer he sells with his name on it from Dave Tooley.
He is like a lot of other guys that sell things in "their name" as it has market value but actually buy them from the guys that invented/market the items to them wholesale.
Nothing wrong with that. Works for both parties.
Just about any shooter who was using Sierras and measuring and tracking ogives will tell you that something changed a little over a year ago. we went from 2-3 distinct groups down to one. Before we had wide variances on ogive and OALs which was insignificent if you seat off the ogive, but was another clear indicator of different dies.
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... we had wide variances on ogive and OALs which was insignificent if you seat off the ogive, but was another clear indicator of different dies.
[/ QUOTE ]I think the only way to verify two or more pointing dies were used for one lot number of bullets is to use an optical comparator to compare ogive shapes.
It's possible that only one die was used, but how far the cored jacket was pushed into it to form the ogive would also determine how far a datum on the base would be from a datum on the ogive. If the machine didn't uniformly ram the cored jacket into the pointing die and stopped different distances away from some reference, the boattail to ogive datum points would easily differ in distance by virtually the same difference in where the ram stopped pushing the cored jacket.
Like full-length sizing a bottleneck case; the more you push it (case or cored jacket) into the die the more the angled part (shoulder or bullet ogive) gets set back. We measure both between a back and front reference and see a difference between case/bullet A, B, C, and so on down the lot of them.
This is getting to be a very interesting thread. I emailed Tubb's site asking what reference diameter is used on their bearing surface comparators. I'll post their answers so all can see.