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Rifles, Reloading, Optics, Equipment
Reloading
using redding instant indicator comparator to measure shoulder bump
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<blockquote data-quote="Bart B" data-source="post: 776382" data-attributes="member: 5302"><p>Two things cause what you're seeing.</p><p></p><p>One is the amount and type of case lube used as well as its lubricity. The easier the case goes into the die when sized, the more the shoulder will get set back. I use a 40-60 mix of Hoppe's No. 9 bore cleaner and STP engine oil treatment for case lube.</p><p></p><p>The other is the amount of spring in the press. The harder the case goes into the die, the higher the die will be when the ram's at the top of its stroke. Most full length sizing dies set properly in the press to bump fired case shoulders from a rifle .002" to go back into the rifle will have a few thousandths clearance between the shell holder and die bottom at the top of their stroke. When folks lower the ram as soon as it toggles over at the top, the spring in the press doesn't have enough time to pull the die back down on the case a thousandth or more.</p><p></p><p>Best thing I know of to have all fired bottleneck cases resize to the same case headspace (head to shoulder datum length) is to use Redding's competition shell holders. These come in .002" steps above the standard .125". Use the one that when the die's set to just barely press against it when the press cams over pushing the case the same distance into the die every time and bumps the shoulder of a fired case from your rifle's chamber back about .003". This makes sized case headspace have consistant dimenions and correct for your semiauto chamber.</p><p></p><p>In second place, what I do, is to tumble cleaned cases in a foam lined can so the case lube's evenly distributed on all cases. That keeps their sized case headspace to a .002" max spread; good enough. </p><p></p><p>Your sized cases should have their case headspace about 3 to 4 thousandths less than actual chamber headspace your rifle has. Unless you have an adjustable chamber headspace gauge to measure yours, use a fired case from your chamber then set the die to make sized case headspace .003" shorter than what the fired case has.</p></blockquote><p></p>
[QUOTE="Bart B, post: 776382, member: 5302"] Two things cause what you're seeing. One is the amount and type of case lube used as well as its lubricity. The easier the case goes into the die when sized, the more the shoulder will get set back. I use a 40-60 mix of Hoppe's No. 9 bore cleaner and STP engine oil treatment for case lube. The other is the amount of spring in the press. The harder the case goes into the die, the higher the die will be when the ram's at the top of its stroke. Most full length sizing dies set properly in the press to bump fired case shoulders from a rifle .002" to go back into the rifle will have a few thousandths clearance between the shell holder and die bottom at the top of their stroke. When folks lower the ram as soon as it toggles over at the top, the spring in the press doesn't have enough time to pull the die back down on the case a thousandth or more. Best thing I know of to have all fired bottleneck cases resize to the same case headspace (head to shoulder datum length) is to use Redding's competition shell holders. These come in .002" steps above the standard .125". Use the one that when the die's set to just barely press against it when the press cams over pushing the case the same distance into the die every time and bumps the shoulder of a fired case from your rifle's chamber back about .003". This makes sized case headspace have consistant dimenions and correct for your semiauto chamber. In second place, what I do, is to tumble cleaned cases in a foam lined can so the case lube's evenly distributed on all cases. That keeps their sized case headspace to a .002" max spread; good enough. Your sized cases should have their case headspace about 3 to 4 thousandths less than actual chamber headspace your rifle has. Unless you have an adjustable chamber headspace gauge to measure yours, use a fired case from your chamber then set the die to make sized case headspace .003" shorter than what the fired case has. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
using redding instant indicator comparator to measure shoulder bump
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