OK, I woke up early 'cause my feet hurt, and I gt to be irreverent.
For all of you weighing powder to the individual kernel: Don't use Reloader powders. They get their burn rate by having some large kernels, some small ones.
I can just see it. "OK, I need one more kernel of powder to get charge weight to .01 grains. Do I add a small one, which will burn a bit faster, or a large one, a bit slower? Do I favor weight, or burn rate? Oh, doctor . . ."
Same with a couple of jugs of VV N-560 I've used. Now the N-550 was much more even . . .
Maybe a property of double-base powders, I don't know. So, why use DB powders? The shoot so damn good. They seem less fussy about pressure regions. Maybe the solution is to buy 100 pounds, sift it all for even size, test each sift for actual burn rate, and then weigh charges to the individual kernel.
Anyone compulsive enough to test this?
So, maybe a RCBS Chargemaster is good enough for range use. Zero before throwing each charge, and lift the pan & recheck the weight with each one thrown. What I do at the range for powder testing, anyway. When I get a charge that shoots really good, I throw about 5 in a film can to take home & weigh on the DI Mk IV, to confirm weight.
Also, Jim Borden pointed out that charges thrown in one temp/humidity can vary from those thrown in another. This by using velocity as the decision factor. Throw one on day one to get velocity of, say, 3,000 fps. Reload a different day to that same MV of 3,000 fps. Oops. Different measure setting, and different weights to get the same MV.
So what really counts is Standard Deviation on MV? Well, yes and no. That gets you the same time in bore for all the bullets, so tuning the load for vertical should no longer be a factor. But equal MV was never all there was to tuning.
Here's another sort-of-secret: Dave Tooley throws all his charges for long-range BR. How come he's got over 70 lifetime Long Range Marksman points -- he doesn't make all the matches, too many other interests. Maybe it's an East Coast thing.
Everybody seen that "First Barrel" thread?