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05-25-2020, 07:16 AM
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Join Date: Dec 2008
Location: Camrose
Posts: 45,129
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Neck Tension And Seating Depths
After reading so many posts about seating depths, and reading about people that crimp because they are afraid of the bullet moving in the case, even in bolt actions, I am curious as to how many actually measure the neck tension, and/or the jump to the lands for their load. Personally, I measure the jump to the lands, and the neck tension for every load.
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Only accurate guns are interesting.
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05-25-2020, 07:38 AM
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Join Date: Jun 2007
Location: Ft. McMurray
Posts: 38,583
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As long as I am using the same cases and dues I don't worry about as long as I have about .0002 or so neck tension
On my Palma Match rifles I pay more attention to the bullet ogive than to nevk tension . I use different seater plugs for a Lapua Scenar than I do for a Match , Hornady , or a Berger because their profiles are very different and the difference is noticeable when doing final testing in load development off the bench at 500 meters .
On my hunting rifles I do not worry about it at all because it doesn't matter near as much when shooting an animal as paying attention to the condition .
Cat
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Anytime I figure I've got this long range thing figured out, I just strap into the sling and irons and remind myself that I don't!
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05-25-2020, 08:53 AM
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Join Date: Dec 2008
Location: Camrose
Posts: 45,129
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Quote:
Originally Posted by catnthehat
As long as I am using the same cases and dues I don't worry about as long as I have about .0002 or so neck tension
On my Palma Match rifles I pay more attention to the bullet ogive than to nevk tension . I use different seater plugs for a Lapua Scenar than I do for a Match , Hornady , or a Berger because their profiles are very different and the difference is noticeable when doing final testing in load development off the bench at 500 meters .
On my hunting rifles I do not worry about it at all because it doesn't matter near as much when shooting an animal as paying attention to the condition .
Cat
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I am not necessarily talking about fine tuning the neck tension to .0005", more like at least verifying that you do have adequate neck tension. Some people just run cases through their dies, and don't take any measurements at all, they just assume that the die will produce adequate neck tension with their cases. I have seen combinations of die/case that allowed the bullet to move during recoil, or even when chambering a round, but instead of addressing the real problem, the shooter added a crimp, and ignored the real issue.
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Only accurate guns are interesting.
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05-25-2020, 09:30 AM
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Join Date: Jun 2007
Location: Ft. McMurray
Posts: 38,583
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Many competition pistol shooters I know crimp their cases for their autos , virtually lever gunners I know do not unless they are shooting really heavy charges .
Never spoke or seen with anybody that crimped to overcome a lack of neck tension in a rifle .
Cat
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Anytime I figure I've got this long range thing figured out, I just strap into the sling and irons and remind myself that I don't!
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05-25-2020, 09:45 AM
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Join Date: Sep 2010
Location: Pincher Creek
Posts: 921
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I am curious, is there more involved than measuring tension based on neck size relative to bullet diameter? Does the friction coefficient between the bullet and the inside of the neck have any influence on the outcome? This of course can be influenced by what one does during the case preparation process.
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05-25-2020, 09:49 AM
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Join Date: May 2007
Posts: 15,838
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Annealing also will make a difference
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“I love it when clients bring Berger bullets. It means I get to kill the bear.”
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05-25-2020, 10:22 AM
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Banned
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Join Date: Mar 2009
Posts: 5,701
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Quote:
Originally Posted by chuck
Annealing also will make a difference
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Turning your necks help too
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05-25-2020, 12:52 PM
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Join Date: Nov 2009
Location: East Central Alberta
Posts: 8,315
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For each lot of brass I do what is necessary to achieve neck tension measured at approximately .002” (difference between the resized brass / seated bullet). This usually involves Nk turning and/or using an appropriate sized bushing. Thereafter, when using that particular lot of brass, I seat without checking between reloads. I seldom anneal before six reload cycles which, depending on how hot I am loading ... may not occur prior to a dozen cycles. I can’t say that annealing makes an appreciative difference in group size, but it does extend the service life of the brass.
Once establishing the jump/jamb sweet spot for a particular bullet, I set the seating die and do not recheck unless accuracy changes.
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05-25-2020, 01:32 PM
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Join Date: May 2007
Posts: 15,838
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Here is how I determine seating depth and neck tension. Pin gauges are the only reliable way I have found to precisely determine actual neck tension. With them you can watch neck tension increase as brass work hardens. And they are cheap. Very very seldom would reloading with standard dies with an expander ball would you encounter neck tension less than .002.
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“I love it when clients bring Berger bullets. It means I get to kill the bear.”
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