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Old November 7, 2011, 11:29 PM   #1
Ricky Bobby
Join Date: October 23, 2011
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Bullet seating depth?

Guys, I'm fairly new to reloading so keep that in mind. I recently decided to start reloading for my Win70 Classic chambered in 30-06. I took a fired case and split the neck of it so that I could force a bullet into it. I have decided to try loading with some 155gr. Nosler Custom Competition bullets & used one of these to insert in the split case. Placed the dummy round into the chamber & closed the bolt carefully. After gently opening the bolt and removing the round I measured it immediately with my calipers. I repeated the process several times to be sure the measurement was consistent, and it was! This measurement will tell me the distance to the lands with this rifle/bullet combination, correct? Does it hurt to take this measurement as a COAL instead of from the ogive of the bullet? Also, where would be a good start for my seating depth when working up my initial test rounds? I was thinking of making my COAL .020" less than the measurement I came up with. Would this be right? That would mean that the bullet would have a .020" jump to the lands, correct? Also, if I'd stick with this COAL when working up test loads & then decide on a powder charge weight that I like, the next step would be to start playing with the seating depth of the bullet, right? Lastly, would you seat them closer to the lands or further away from the original starting point? Thanks & I hope I wasn't to long winded!
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Old November 8, 2011, 12:24 AM   #2
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0.020" - 0.030" (paperclip diameter) off the lands is the classic starting point, and usually
yields excellent results right there.

155gr. Nosler Custom Competition
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.

Last edited by mehavey; November 8, 2011 at 08:32 AM.
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Old November 8, 2011, 02:06 AM   #3
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Assuming the two methods disagree somewhat, use the cleaning rod measurement to establish your failsafe OAL.
+1 on that.

If you are going to get into experimenting with different bullets for the 30-06 you may want to consider the Hornady L-N-L OAL gauge and modified case.

Si vis pacem, para bellum
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Old November 8, 2011, 07:27 AM   #4
old roper
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Here is something to look at on seating depth
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Old November 8, 2011, 07:56 AM   #5
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Lastly, would you seat them closer to the lands or further away from the original starting point?
I would start out at .020 off the lands and reduce OAL, (farther away) from there. Increasing OAL will also increase pressure, by seating deeper you will decrease pressure.
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