A long & rambling post that may not be worth your time.
Boyd,
My post was riddled with "ifs" on purpose. As you know, I shoot the long-range game. I happen to use a Juenke machine. I also accept Eric Steckers analysis of the machine, so I don't use it exactly as its designer intended. I test two things: (1) how much the boattail, if there is one, is off-center from the shank, and (2) I measure from the base of the bullet to where the ogive starts. (2) isn't exactly bearing length, because the length of the boattail is included.
(1) is actually measured in "deviation units," what the machine was designed to do. (2) is a (relative) absolute grading. "Relative" is in parens because you can use the "absolute" number only in you don't change any of the dials, and recheck it over time (it is sensitive to line voltage).
OK. The other things I do: (1) is to put the Wilson seater stem in the lathe and with a small boring bar, change the angle to more closely match the bullet ogive, and open the hole up generally so the stem picks up the bullet quite close to the beginning of the ogive. And (2), the body of the seater is shortened so that the shoulder stops the case. If the case head stands .001 or so proud, so be it.
I go into all this not to recommend it to anyone, but because it is what I do, and it has worked for me. All the other things that have been deemed "critical" for the long-range game on the several forums have not mattered for me, and I don't do them. If you do and that works for you, so be it.
As for how critical seating depth is generally: if I were to find that a .001 or .002 change in seating depth was crucial in one of my barrels, I just wouldn't use that depth. For all the reasons Boyd mentions, and others. At the moment, I shoot a .30 that likes to be jammed so hard that the marks on the bullets are quite long. Except for the fact that it would offend all the people who feel that "the number" must be both precise and exact, I'd say I jam them .040. It may not be .040, but I can repeat it. Over the last half of last season and the first half of this season. the rifle has gotten me into more shootoffs than not, which is my way of gauging performance. It is NOT a hummer barrel.
The light gun I shoot is a new-to-me .338/404, with Berger 300-grain hybrids. The rifle seems to shoot best with a ".020" jump. Yours may not. Sample size real small, but I won my relay for score Sat, and while I didn't get centered up as well as the guy who won with a 50, my group was 3.7xx inches, which at 1K is considered worth having (the group in the score shootoff doesn't count). Well, just a couple data points, but it is a succession of such data points that leads me to conclude things are or are not working. BTW, that big bullet is so long I can't check the boattail on the Juenke. I can check where the ogive begins, and I'd say congratulations to Berger, those are fine bullets.
Why do I go into this, esp. as a response to Boyd? Because I think he's right -- not so much right in the specifics of his technique as for the reasons for his technique. Obviously, I think I'm right too. Other things to consider: Don't you think the dimensions of the chamber change a bit as you fire rounds and heat it up? Maybe not with the PPC; I put 450 grains of powder down the barrel with each five shots. Add 4 sighters, and you have 800 grains of powder burned in about 3 minutes.
There are other ways to deal with the phenomena Boyd points out, but *what* he points out is a fact. There are obviously other ways to approach bullet seating depth, but what I point out is also at issue. To anyone who uses a Stony Point, or a Sinclair, or whatever tool, remember all the other tooling you use in reloading, and how that can effect the end result. And finally, remember that for some of us, "proof" is not one group, or even one range session. It is performance under what Jackie calls "the heat of competition," over a series of matches.
