Seating inconsistency

[paulsol_15]

Loaded 40 rounds and 10 of these seated approx .015 deeper than they should have. For curiousity sake, on the bullets that where too deep, I pulled bullets approx .020-.025 and reseated. This resulted in the bullets seating where they should.

All cases had the same neck tension, were cleaned, deburred etc.

All brass was once fired.

I measured several bullets at random, and they only differed about .002 in length at most.

Can anyone explain this?

 

[wilbar]

It happens a lot, apparently competition seater dies will eliminate or reduce this...but I've developed a technique that keeps them a little more consistent.

The shape of the seater cup is hitting the ogive or tip at different angles is the nature of the problem so when I'm seating bullets I seat then lower the ram part way and rotate the bullet then seat again. This is highly dependent on what bullet or how much variance I'm experiencing at the time. Some bullets don't require it and some I raise the ram 3 times at different rotation points to get a more uniform OAL.

JMHO

Willy

 

[silverfoxdj]

Good tip.. TKS

 

[IMR4320]

My Lee seating die for 308 Win fluctuates .004 to .007. So to correct for that I start seating with the die loosened a bit to get to my 2.805" dimension, run a batch then tighten up a slightly and re-run those rounds that ended up too long to get to consistent OAL. It is a bit back and forth but it is the best I can come up with without spending big $$$ for comp. seating die.

 

[OldDude]

My Lee seating die for 308 Win fluctuates .004 to .007. So to correct for that I start seating with the die loosened a bit to get to my 2.805" dimension, run a batch then tighten up a slightly and re-run those rounds that ended up too long to get to consistent OAL. It is a bit back and forth but it is the best I can come up with without spending big $$$ for comp. seating die.

Have you measured the ogive length and compared it to the OAL for the same cartridges?
I did so with a small batch of 30-06, and found while there was a substantial variation in the overall length, the length of the ogive was a lot more consistent. This was with an RCBS seating die; I haven't done the same test with a Lee seater....

Stan