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Rifles, Reloading, Optics, Equipment
Reloading
Which die should I use?
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<blockquote data-quote="Bart B" data-source="post: 115178" data-attributes="member: 5302"><p>[ QUOTE ]</p><p>When you guys talk about "bumping" the shoulder back, what does this mean and how do you do this? </p><p></p><p>[/ QUOTE ]Virtually all full-length sizing dies will set the fired case shoulder back from its fired position when the die's screwed far enough down into the press. Most die maker's instructions say to set the die to touch the shell holder with the ram all the way to the top then lock it in place. If the die's set too high, the fired case shoulder won't be pushed or "bumped" back far enough and such sized cases may be hard or impossible to chamber. Too often, folks set the die too far down causing excessive headspace with bottleneck cases therefore getting poor accuracy and short case life; they go to neck-only resizing which helps accuracy but if they backed the die out a bit things would be better.</p><p></p><p>Best accuracy with full length sized cases typically happens when the case shoulder is set back .002- to .003-inches from its fired position. It take a shoulder headspace gage to measure this. Belted cases can have their shoulder set back twice that much as they should headspace on the belt, not the shoulder, for best accuracy.</p><p></p><p>When a case shoulder gage is used, the die can be set then locked in place for fired cases in a particular rifle chamber. A different chamber for the same cartridge may well have different shoulder headspace so the die would have to be reset.</p><p></p><p>Some neck only sizing dies have a shoulder so the fired case neck can be "bumped" back a bit. Even neck only fired cases grow a bit in shoulder headspace and they need to be "bumped" once in a while. I've tried them for a couple of cartridges but didn't get nearly as good of accuracy as full-length sized cases with proper shoulder set back.</p></blockquote><p></p>
[QUOTE="Bart B, post: 115178, member: 5302"] [ QUOTE ] When you guys talk about "bumping" the shoulder back, what does this mean and how do you do this? [/ QUOTE ]Virtually all full-length sizing dies will set the fired case shoulder back from its fired position when the die's screwed far enough down into the press. Most die maker's instructions say to set the die to touch the shell holder with the ram all the way to the top then lock it in place. If the die's set too high, the fired case shoulder won't be pushed or "bumped" back far enough and such sized cases may be hard or impossible to chamber. Too often, folks set the die too far down causing excessive headspace with bottleneck cases therefore getting poor accuracy and short case life; they go to neck-only resizing which helps accuracy but if they backed the die out a bit things would be better. Best accuracy with full length sized cases typically happens when the case shoulder is set back .002- to .003-inches from its fired position. It take a shoulder headspace gage to measure this. Belted cases can have their shoulder set back twice that much as they should headspace on the belt, not the shoulder, for best accuracy. When a case shoulder gage is used, the die can be set then locked in place for fired cases in a particular rifle chamber. A different chamber for the same cartridge may well have different shoulder headspace so the die would have to be reset. Some neck only sizing dies have a shoulder so the fired case neck can be "bumped" back a bit. Even neck only fired cases grow a bit in shoulder headspace and they need to be "bumped" once in a while. I've tried them for a couple of cartridges but didn't get nearly as good of accuracy as full-length sized cases with proper shoulder set back. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Which die should I use?
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