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Rifles, Reloading, Optics, Equipment
Reloading
Setting up a Full Length die.
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<blockquote data-quote="AJ Peacock" data-source="post: 303086" data-attributes="member: 4885"><p>Woods,</p><p></p><p>Yep, It has always seemed to me that new brass had more spring back. Brass that has been used a lot tended to measure longer and require more resizing.</p><p></p><p> At first reading, I didn't agree with the Hornady engineers, but after some consideration, I think I do. It makes sense that as a metal gets work hardened, it tends to be more resistant to being deformed (more than when it was softer). I am certain that brass that has been shot multiple times are harder to resize. I'm also certain that once fired brass is smaller (headspace wise) than brass shot multiple times. It may be that we are trying to compare apples and oranges, and that we are using the term 'spring back' inappropriately.</p><p></p><p>If you think about shooting/resizing/shooting/resizing as a process, a cartridge will actually grow in diameter a little each cycle (because we don't have an easy method for sizing the diameter more as the brass becomes harder). We can push the shoulder back more as the brass gets harder, but we can't adjust the diameter of our dies (collet/mandrel dies excepted). </p><p></p><p>So to be correct, work hardened brass has more 'spring back', but once fired brass ends up smaller than the chamber (as compared to brass fired multiple times) because it's only been through one cycle of firing/resizing.</p><p></p><p>If you fire the same brass a half dozen times, it will pretty closely represent your chamber dimensions. New brass hasn't been processed enough times to move from it's orignal size to the chamber dimensions yet. It's tough to compare the forces involved in firing a cartridge (lots of pressure and heat) and the forces involved in resizing a piece of brass (not much pressure and almost no heat).</p><p></p><p>I read the thread you referenced and one thing intrigued me. One of the posters said that a piece of brass that is resized will grow over time (without being fired) and will behave differently whether it had been annealed or not. I went down and measured some reloads and once fired brass that has been sitting since 7/2007 and the measurements have not changed (lucky that I had documented the dimensions of the once fired and reloaded cartridges!).</p><p></p><p>OK, enough rambling.</p><p></p><p>AJ</p></blockquote><p></p>
[QUOTE="AJ Peacock, post: 303086, member: 4885"] Woods, Yep, It has always seemed to me that new brass had more spring back. Brass that has been used a lot tended to measure longer and require more resizing. At first reading, I didn't agree with the Hornady engineers, but after some consideration, I think I do. It makes sense that as a metal gets work hardened, it tends to be more resistant to being deformed (more than when it was softer). I am certain that brass that has been shot multiple times are harder to resize. I'm also certain that once fired brass is smaller (headspace wise) than brass shot multiple times. It may be that we are trying to compare apples and oranges, and that we are using the term 'spring back' inappropriately. If you think about shooting/resizing/shooting/resizing as a process, a cartridge will actually grow in diameter a little each cycle (because we don't have an easy method for sizing the diameter more as the brass becomes harder). We can push the shoulder back more as the brass gets harder, but we can't adjust the diameter of our dies (collet/mandrel dies excepted). So to be correct, work hardened brass has more 'spring back', but once fired brass ends up smaller than the chamber (as compared to brass fired multiple times) because it's only been through one cycle of firing/resizing. If you fire the same brass a half dozen times, it will pretty closely represent your chamber dimensions. New brass hasn't been processed enough times to move from it's orignal size to the chamber dimensions yet. It's tough to compare the forces involved in firing a cartridge (lots of pressure and heat) and the forces involved in resizing a piece of brass (not much pressure and almost no heat). I read the thread you referenced and one thing intrigued me. One of the posters said that a piece of brass that is resized will grow over time (without being fired) and will behave differently whether it had been annealed or not. I went down and measured some reloads and once fired brass that has been sitting since 7/2007 and the measurements have not changed (lucky that I had documented the dimensions of the once fired and reloaded cartridges!). OK, enough rambling. AJ [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Setting up a Full Length die.
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