HI Barry
Interesting post mate
I agree with you that my indicated method is crude, indeed very crude, but it was a method to try with the absence of the right tools. In reality there is no substitute for the right gear if you wish to make consistent ammo.
I agree that my stony point OAL gauge, and combined with my good caliper, can also give inconsistent reading. The whole thing, gauge and caliper, must be totally square to one another to be able to achieve total consistency. A better approach for it would be to have a one piece jig, but the OAL is inexpensive and better than nothing.
For interest, my BJD’s prefer a slightly longer jump than the sierras, and while I have not checked them for group at 600m at 300m they group at 27 – 31mm (vertical displacement) for 5 shots. So, I’m more than happy with that and my own reloading techniques, and achieving the ‘right jump for my rife’ only took 4 different seating depths to test involving around 40 rounds of ammo in total.
Note, that because of my long throat I cannot get any 155gnr’s to touch the lands, so, and as another TRG user said to me, we have a 20 cm jump
As far as techniques go, uniformity and consistency is always the key, but you do not have to be a slave to you ammo or let it consume your time. For instance I use a redding mic ‘neck bushing’ sizing die and mic bullet seater. The mic die is not essential and the only reason I got it is I reload for 2 x 308’s with different seating depths.
I clean all my cases thoroughly, inside and out.
I check all my cases for length with a caliper and group them.
I do not full length size unless necessary, and, I only neck size the first 5mm of the neck as I find this reduces potential run out greatly.
I chamfer all my case necks inside and out every time.
And that’s about it, and my ammo is very consistent, its me using it that isn’t …
Also, Peter is quite correct, as your throat wears you need to re set you seating depth.
Tony
MBRC F-Class standard ... and proud of it!