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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Die setup for .300 Tommy questions..
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<blockquote data-quote="BountyHunter" data-source="post: 26647" data-attributes="member: 12"><p>FL sizing with shoulder bump is easy to do, but first you have to know where you are starting from.</p><p></p><p>Take a stoney point set that has the inserts for measuring off the datum line or have your gunsmith take a barrel stub and make a shoulder bump guage. Measure virgin brass and once fired brass and record data. At some point (depends on cases and chamber) you will start getting cases that are hard to close. At this point take 2-3 hard to close cases and take a candle and smoke neck and shoulder. Measure datum line measurement before smoking. This will tell you how far your case datum line is moving. </p><p></p><p>Turn die up couple turns, size and see how far comes down the neck. Adjust die down a little, resmoke and repeat. Once comes down to just bumping shoulder and datum line. Clean case, measure and see where you are at. You want .002 bump back, no more. Repeat and adjust to get no more than .002. You can now record this measurement and lock die down to this point. That gives you FL size with shoulder bump each time. Less work on brass.</p><p></p><p>Another point that has been discussed. If you just routinely lock dies down at the "camover point" you could be getting .004-.008 shoulder/datum line movement. Ideal is .002 no more.</p><p></p><p>Second it is possible to cam over too much and move datum line back to point that they will not chamber. Been there done that. </p><p></p><p>Key is to record datum line measurements from virgin, once fired and point where they are hard to close. That way you know what you are dealing with.</p><p></p><p>BH</p></blockquote><p></p>
[QUOTE="BountyHunter, post: 26647, member: 12"] FL sizing with shoulder bump is easy to do, but first you have to know where you are starting from. Take a stoney point set that has the inserts for measuring off the datum line or have your gunsmith take a barrel stub and make a shoulder bump guage. Measure virgin brass and once fired brass and record data. At some point (depends on cases and chamber) you will start getting cases that are hard to close. At this point take 2-3 hard to close cases and take a candle and smoke neck and shoulder. Measure datum line measurement before smoking. This will tell you how far your case datum line is moving. Turn die up couple turns, size and see how far comes down the neck. Adjust die down a little, resmoke and repeat. Once comes down to just bumping shoulder and datum line. Clean case, measure and see where you are at. You want .002 bump back, no more. Repeat and adjust to get no more than .002. You can now record this measurement and lock die down to this point. That gives you FL size with shoulder bump each time. Less work on brass. Another point that has been discussed. If you just routinely lock dies down at the "camover point" you could be getting .004-.008 shoulder/datum line movement. Ideal is .002 no more. Second it is possible to cam over too much and move datum line back to point that they will not chamber. Been there done that. Key is to record datum line measurements from virgin, once fired and point where they are hard to close. That way you know what you are dealing with. BH [/QUOTE]
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Die setup for .300 Tommy questions..
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