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Rifles, Reloading, Optics, Equipment
Reloading
Load development and seating depth?
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<blockquote data-quote="Ackley Man" data-source="post: 494287" data-attributes="member: 16583"><p>Adjusting seating depth is traditionally the final step in fine turning a load unless you plan on using a load charge that is running on the ragged edge of maximum simply because seating depth can have a profound effect on pressure. As you probably already know, COAL is a worthless measurement except when applied to magazine clearances. It is a measurement established by SAAMI for use by arms and ammo manufacturers in an attempt to standardize measurements for each given caliber. Unfortunately the specs are not followed as closely as we would like by either of the manufacturers. Seating depth measurements must be based upon a leade <em>(beginning of rifling) </em>to case base measurement. A seating depth gauge is required to establish this measurement in conjunction with the particular bullet you will be using. Each bullet make and style change will require a new measurement because it will be established from the bullet ogive. As a double check for your measurement, equally square lands marks on your bullet will indicate a +.005 into the lands seating. If you intend to use a particular rifle mostly for hunting you probably do not want to seat bullets into the lands more than .005 because if you need to eject a round from the chamber the bullet may stick in the rifling. There is almost nothing worse than dumping a case full of powder into the trigger group. Personally, after I am satisfied with my load based upon selected muzzle velocity I test seating depth with three shot groups, after shooting one or two bore fouler rounds, being sure to allow the barrel to cool between groups. Normally I start with "0" the go to the plus side (+5 & +10) then to the negative side (-10, -20, -30). One of the three shot groups will exhibit smaller measurements. You can then additionally fine tune by going to the + or - side of the best group. Good luck with your testing.</p></blockquote><p></p>
[QUOTE="Ackley Man, post: 494287, member: 16583"] Adjusting seating depth is traditionally the final step in fine turning a load unless you plan on using a load charge that is running on the ragged edge of maximum simply because seating depth can have a profound effect on pressure. As you probably already know, COAL is a worthless measurement except when applied to magazine clearances. It is a measurement established by SAAMI for use by arms and ammo manufacturers in an attempt to standardize measurements for each given caliber. Unfortunately the specs are not followed as closely as we would like by either of the manufacturers. Seating depth measurements must be based upon a leade [I](beginning of rifling) [/I]to case base measurement. A seating depth gauge is required to establish this measurement in conjunction with the particular bullet you will be using. Each bullet make and style change will require a new measurement because it will be established from the bullet ogive. As a double check for your measurement, equally square lands marks on your bullet will indicate a +.005 into the lands seating. If you intend to use a particular rifle mostly for hunting you probably do not want to seat bullets into the lands more than .005 because if you need to eject a round from the chamber the bullet may stick in the rifling. There is almost nothing worse than dumping a case full of powder into the trigger group. Personally, after I am satisfied with my load based upon selected muzzle velocity I test seating depth with three shot groups, after shooting one or two bore fouler rounds, being sure to allow the barrel to cool between groups. Normally I start with "0" the go to the plus side (+5 & +10) then to the negative side (-10, -20, -30). One of the three shot groups will exhibit smaller measurements. You can then additionally fine tune by going to the + or - side of the best group. Good luck with your testing. [/QUOTE]
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Reloading
Load development and seating depth?
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