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Rifles, Reloading, Optics, Equipment
Reloading
Concentricity Minimum
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<blockquote data-quote="barefooter56" data-source="post: 1024178" data-attributes="member: 85389"><p>RustyRick,</p><p>Couple things. A concentricity gauge is really a diagnostic tool to help you find where and what is causing the run out issue. Basic rule of thumb we use is .000 to .005 run out usually will not affect accuracy. Always use a fired ( once is ok) case. Think of your rifles chamber as the last step in the forming process of that cartridge case. Pre-load the the dial indicator on the neck of the cartridge case you are checking at least .010 to .015 so the probe will not lose contact with the neck as you rotate the cartridge case. Re-zero the face of the indicator. With the first step you are checking the cartridge case about in the middle of the neck right out of the chamber. If the rifles chamber was reamed correctly the run-out should be right about zero. Step two, run the cartridge case through the neck or full-length die you are using and check on the neck at the same point of the neck as step one. Note the amount of run-out. Step three is to seat a bullet in the cartridge case. Here you want to place the probe of the dial indicator as close to the casemouth /bullet junction as you can get it without the probe contacting the neck. Note the run-out. Some times you will find that seating the bullet can actually decrease the run-out measurement from the neck or full-length sizing check! Following these steps you will find where the problem is and can concentrate on that point to fix the problem. Can save you a lot of money on dies ! I have fixed a problem with something as simple as backing the lock screw in the lock ring back away from the threads on the die body and letting the die "float" in the threads. Glen Zedikers book "Handloading for Competition" has many more easy hardware store fixes for die issues and is a good reference book to have in your reloading library. If you have the Hornady tool pay close attention to the instructions. They do list a run-out range where you can use the "bullet pusher" to straighten a round. Using the bullet pusher on rounds with more run-out can result in just loosening the bullet in the neck. I use the Sinclair tool because of the ease of rolling the case on the fixed ball bearings and the fact that you can check the cartridge case by itself and/or with a bullet seated.</p><p>The reason you don't check the bullet out farther is that the bearing surface of the bullet is what contacts the lands. The Hornady tool is really made to be used on a loaded round only. Factory or reloaded. </p><p>Take care,</p><p> Phil Hoham</p><p>Berger Bullet Tech</p></blockquote><p></p>
[QUOTE="barefooter56, post: 1024178, member: 85389"] RustyRick, Couple things. A concentricity gauge is really a diagnostic tool to help you find where and what is causing the run out issue. Basic rule of thumb we use is .000 to .005 run out usually will not affect accuracy. Always use a fired ( once is ok) case. Think of your rifles chamber as the last step in the forming process of that cartridge case. Pre-load the the dial indicator on the neck of the cartridge case you are checking at least .010 to .015 so the probe will not lose contact with the neck as you rotate the cartridge case. Re-zero the face of the indicator. With the first step you are checking the cartridge case about in the middle of the neck right out of the chamber. If the rifles chamber was reamed correctly the run-out should be right about zero. Step two, run the cartridge case through the neck or full-length die you are using and check on the neck at the same point of the neck as step one. Note the amount of run-out. Step three is to seat a bullet in the cartridge case. Here you want to place the probe of the dial indicator as close to the casemouth /bullet junction as you can get it without the probe contacting the neck. Note the run-out. Some times you will find that seating the bullet can actually decrease the run-out measurement from the neck or full-length sizing check! Following these steps you will find where the problem is and can concentrate on that point to fix the problem. Can save you a lot of money on dies ! I have fixed a problem with something as simple as backing the lock screw in the lock ring back away from the threads on the die body and letting the die "float" in the threads. Glen Zedikers book "Handloading for Competition" has many more easy hardware store fixes for die issues and is a good reference book to have in your reloading library. If you have the Hornady tool pay close attention to the instructions. They do list a run-out range where you can use the "bullet pusher" to straighten a round. Using the bullet pusher on rounds with more run-out can result in just loosening the bullet in the neck. I use the Sinclair tool because of the ease of rolling the case on the fixed ball bearings and the fact that you can check the cartridge case by itself and/or with a bullet seated. The reason you don't check the bullet out farther is that the bearing surface of the bullet is what contacts the lands. The Hornady tool is really made to be used on a loaded round only. Factory or reloaded. Take care, Phil Hoham Berger Bullet Tech [/QUOTE]
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