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seating depth increments?

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Unread 02-23-2004, 09:13 PM
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Join Date: Jul 2001
Location: Walla Walla, WA
Posts: 174
seating depth increments?

My gunsmith suggested that my 6-284 would most likely shoot best with the Sierra 107 matchking bullet seated 0.010 to 0.015 into the lands. I plan to go out and try several different seating depths and wonder what increment to use? Should I try just touching the lands, 0.005, 0.010 and 0.015 into the lands or should I try in 0.001 or 0.002 increments or what? Thanks, Rufous.
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Unread 02-25-2004, 09:26 PM
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Join Date: Jan 2003
Location: centre,alabama
Posts: 948
Re: seating depth increments?

I start touching the lands,usually this will work if not drop back two thousands and so on. There will be a sweet spot some where!
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Unread 02-27-2004, 03:08 PM
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Join Date: Jun 2007
Location: Wilmington NC
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Re: seating depth increments?

I like to test for serious load development at 300-400 yds under no wind conditions early in morning or evening, firing several groups to confirm what I think is serious load.

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Unread 02-27-2004, 03:12 PM
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Join Date: Dec 2001
Location: Long Island, New York
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Re: seating depth increments?

I don't believe in seating bullets to "just touching the rifling", particularely with production bullets.
First of all, production bullets (and customs to a lesser extent)can only be produced within certain tolerances. Base to ojive distance varies, curvature of ojive varies, bullet length varies and on and on.

Additionally, it is difficult to get an EXACT measurement of your chamber/throat with the current maesuring tools. If you are within 1-2 thousandths than thats pretty good, but you also have to remember that the throat is always receeding slightly too. It doesn't take much for a throat to erode .001".

Given the inevitable variences of a few thousandths, if you try to "just touch the rifling" than one round may do just that while another is .001" into the rifling and another is .001" off the rifling. That is three very different conditions, and all within .002" of variation from bullet base to bearing surface of the bullet.

I much rather work .005"-.010" into or off-of the rifling. This way a variation of a few thousandths will not cause a significant change in engagement.

Provided that the wind is favorable, group size changes are normally more evident as range increases.

Just my thoughts - VH

[ 02-27-2004: Message edited by: Varmint Hunter ]
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Unread 02-27-2004, 11:57 PM
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Join Date: Feb 2004
Location: Portland
Posts: 14
Re: seating depth increments?

I agree with VH. You cannot hold those kinds of tolerances to be "just touching the lands". Some will be just touching and some will not.
I seat my Berger VLD's in .308 .015 into the lands.
If you want to seat into the lands, I would start at .010 into the lands and then proceed with increments of .005.
I say to start with them .010 in so that with your possible tolerance stack, you will still have all bullets touching the lands for sure.
My .02
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Unread 02-28-2004, 12:35 AM
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Join Date: Feb 2004
Location: Wyoming
Posts: 433
Re: seating depth increments?

At what distance would you be best able to see the effects of the seating depths? 100, 200, 300....?
Never pass up a kool-aid stand or lemonade stand. Remember it is a young American learning the American dream.
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Unread 03-01-2004, 12:52 AM
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Join Date: Dec 2001
Location: Pennsylvania
Posts: 230
Re: seating depth increments?

This may be a dumb question but can't you get and or customize a bullet seater to contact the bullet with the exact same taper and contact point as your lands? Or is it that the seater being full contact all the way around could differ since the rifling only contacts the amount of lands that you have? And if this is the case, that the bullet seater may touch a "high" spot around an imperfect bullet, would this not error on the safe side? Meaning if a seater were set up this way a bullet could never be seated too long?

Just some questions,
Thanks, HPA

Alright I just reread again and I think I got it. The error on the safe side could be the cause of inaccuracy therefore either crammed in or away from the lands, gotcha.

[ 03-01-2004: Message edited by: HoytemanPA ]
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