Discussion Forums

jason

I managed to find a second hand concentricity gauge. So iv been measuring up a storm.
So far I'm fairly happy with fired and sized cases. Some vary a bit but within spec. Iv seen a few half thou readings so I know my gauge has the tolerance in it to measure down that low. (Errors or rough spots in the gauge)
First I graded my rounds to 1.5 thou under or over. In my ammo box either good or bad.
I noticed that neck run out was on pah with projectile run out or close enough. For example the neck was measuring close enough to what the projectile was measuring.
But then I had a few that were a fair way out. Let's say the case neck was 1.5 thou but the projectile was around four thou.

So i guess this is a long winded way of asking shouldn't the fairly good neck keep the projectile on pah? As most of the rounds were. How often or likely are projectiles out of round? I know oal varies a bit. I try to keep my seating rythum the same for each round, or is the odd out of time rythum enough to see differences. I usually start seating, rotate then carry on.
Can a bad seating die show results of a good neck yet bad projectile run out? Wouldn't the neck influence the projectile?

any experiences with concentricity measurments and results welcome here.
(You knew this thread was coming didn't you nathan) haha.