0.020" - 0.030" (paperclip diameter) off the lands is the classic starting point, and usually
yields excellent results right there.
Quote:
155gr. Nosler Custom Competition
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Because that bullet is a precision hollow point, you can depend on an OAL measurement being
far more consistent than w/ a soft point. Go ahead and use the OAL.
Do yourself a favor, though. Double check OAL w/ the cleaning rod method below. If the
two split-case/cleaning rod methods agree, great. But I'll bet the split case method gives
you a longer distance-to-lands because that technique forces the bullet into the lands somewhat
--no matter how careful/gentle you are.
Cleaning Rod Method
Gently push a bare bullet into the chamber and up against the rifling using a wooden dowel.
Use a cleaning rod from the muzzle to slightly push the bullet back & forth on-again/off-gain
from the rifling against the dowel. When satisfied that the bullet is just barely contacting the
rifling, mark the cleaning rod w/ a razor blade right at the muzzle.
A good starting point for OAL is then an assembled cartridge 20-30 thousandths shorter than that
-- i.e, the cleaning rod will sink deeper into the barrel by the diameter of a small paperclip
before the bullet stops it.
Assuming the two methods disagree somewhat, use the
cleaning rod measurement to establish your failsafe OAL.