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Uniform OAL

When cheaking oal with dig calipers have noticed different oaLengths, Im using lapua 243 & 308 brass with all same lengths, I measure the lapua scenars and sort them in same lengths i am useing rcbs comp dies and seater and neck all brass, am i write in thinking that the vairying lengths are down to slight differencies in contact with seater dies and curveture of the bullet ifso slight length difference shouldnt matter because the bullet curve length measurement would be the same? or should for best accuracy i try and keep to same bullet lengths? Paul T.
 
I use the Stoney Point adaptor/tool on all my loads. The bullets can get bumped around in the box and the tips get damaged so a measurement can differ from one bullet to the next.
With the Stoney Point tool, you don't have to worry about that problem. I use RCBS Compitition Seater dies on all my rounds and they come out right where I set them.
 
If you measure the oal of the bullets alone, you will find as much as .010" or more difference in a box of 100 bullets. Noted exceptions to this are JLK and Lapua bullets.I measured a box of 100 JLKs and found only .003" difference in oal for those 100 bullets. I found similar results with Lapua Scenars.

Scott Parker

Bakersfield CA
 
Here are a couple links you might find interesting -

http://www.benchrest.com/forums/showthread.php?t=28867

http://www.benchrest.com/forums/showthread.php?t=27109&page=1&pp=15&highlight=seating+depth
 
I use the Davidson seating depth checker. The nose piece alone can be used to measure to the ogive and sort bullets. Add the base, with a micrometer seater die, you can seat bullets 10-20 thou long, then measure as you bring em down to hit exact OAL every time. Just a little time consuming, but it does the job.
 

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