I've had problems with annealing. I don't have a fancy machine to do it, I do it by hand. So I intentionally work harden the necks a bit to try to hopefully bring them to a happy medium. I doubt that the work hardening they get from hand hand pressing is anything close to what happens when they get hit by 50,000 PSI And stretched to meet the neck walls of the chamber. But I could be wrong!
If you have any brilliant ideas to decrease my velocity dispersion I'd be happy to hear them! I use a Lee perfect powder thrower, and typically am within .1 grains. But this is Varget, and it doesn't meter perfectly. I have a charge master, but it is somewhat slower, and I haven't seen much of a difference in the past.
Shot number four still doesn't make any sense. Only 2 ft./s can't make that much difference. I'm guessing it has something to do with the particular hold on the rifle for that shot.
Hi Docsleepy,
moving away from the first shot flying.
OK I understand what you are trying to achieve on the case hardening, I do think that you will battle to control the consistency and therefore neck tensions could differ significantly. This will impact on accuracy and bullet speeds. Is there any way you can duplicate your shooting exercise with brand new cases to remove most the variability of neck tension?
Throwing to 0.1gr is fine and you can't see the difference at 100yds. Checked the Sierra software and you are close with your load vs. speed. Sierra also shows that you have an effective zero on the rifle at 260 yards to get 3" high at 100yds.
The shot with 2fps difference in vertical the could be the shooter, I have experienced similar.
Have you considered a different bullet weight? Some bullets weight simply don't agree with the rifle. My 30-06 shoots a 165 better than a 180 although I still load 180's for hunting.
When load developing I get a couple of patterns that can present, one is vertcal dispersion, the other is lateral dispersion and as I get closer to the perfect load the pattern become more random and triangular (use three shots for development). Is there a chance that your load may not be fully developed?
You only have a lateral dispersion of 0.75" which is great. So if you barrel was shot out how come it only affects performance in the vertical plane?
So theoretically the factors that give varying vertical displacement are;
- Erratic firing pin strike (weak / broken spring) you have discounted this already.
- Front rest being too hard, you have discounted this already.
- Variable loads, discounted at .1gr difference.
That leaves possibly
- Bullet weight not perfectly suitable
- Varying neck tension
- Breathing control
- Load not on an accuracy node.
Unfortunately I have no brilliant ideas but this is what I would do. Either nothing and wait for the new barrel and hope that sorts the matter out or;
- Get some brand new brass
- Do the Dan Newberry's OCW development routine and ensure that your load with new brass is correct and on an accuracy node.
- Once the load is established then conduct your cold firing routine with and without grease.
Good luck in your pursuits.