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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
.243 Barrel Life and Cryogenics
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<blockquote data-quote="Trickymissfit" data-source="post: 1185512" data-attributes="member: 25383"><p>now that's the question of the day! I know they have a set of factor numbers for artillery with a new barrel when a certain number is reached. Be pretty hard to do with a rifle what with chamber pressures all over the place. Let alone heat. What I think (just me) is that one would have monitor the bore every fifty rounds or so for heat cracks (some call it checkering). At least that will give a good hint of a time line. </p><p></p><p>The next serious issue is the barrel alloy. Lets just say you bought a barrel blank cut from 4350 prehard steel, or even 416 SS steel. Fired about 850 seriously hot loads thru it. Then the throat was beginning to go south. You call JE or Shortgrass to have them get ready for a rebarrel job out of the same 4350 or 416 steel. Next barrel goes south at 775 shots. But you say it's the same kind of barrel! Wrong! Steel varies from lot to lot number, and in many cases ingot to ingot. What I'm saying is that there's just no good way to figure barrel life that rings a bell with me. I might add here that the only way to stress relieve a barrel without softening the metal, is to try a deep freeze, or induce compressive stress (won't be much help). I seriously doubt the deep freeze will help as well. </p><p></p><p>We start out with fine cut barrel that is machined as best as we can get. We check the barrel hardness, and it comes in at 32RC no matter where we test it. Still there's no way to check the bore. About the only thing else todo is a sonic test or X-ray the steel.</p><p>Yet every time we pull the trigger, we shoot heat thru the barrel. The heat tends to draw back the steel (lessons the RC number). Still not the entire blank, but the surface of the bore (maybe .030" deep at worst). Of course that will increase the wear. </p><p></p><p>gary</p></blockquote><p></p>
[QUOTE="Trickymissfit, post: 1185512, member: 25383"] now that's the question of the day! I know they have a set of factor numbers for artillery with a new barrel when a certain number is reached. Be pretty hard to do with a rifle what with chamber pressures all over the place. Let alone heat. What I think (just me) is that one would have monitor the bore every fifty rounds or so for heat cracks (some call it checkering). At least that will give a good hint of a time line. The next serious issue is the barrel alloy. Lets just say you bought a barrel blank cut from 4350 prehard steel, or even 416 SS steel. Fired about 850 seriously hot loads thru it. Then the throat was beginning to go south. You call JE or Shortgrass to have them get ready for a rebarrel job out of the same 4350 or 416 steel. Next barrel goes south at 775 shots. But you say it's the same kind of barrel! Wrong! Steel varies from lot to lot number, and in many cases ingot to ingot. What I'm saying is that there's just no good way to figure barrel life that rings a bell with me. I might add here that the only way to stress relieve a barrel without softening the metal, is to try a deep freeze, or induce compressive stress (won't be much help). I seriously doubt the deep freeze will help as well. We start out with fine cut barrel that is machined as best as we can get. We check the barrel hardness, and it comes in at 32RC no matter where we test it. Still there's no way to check the bore. About the only thing else todo is a sonic test or X-ray the steel. Yet every time we pull the trigger, we shoot heat thru the barrel. The heat tends to draw back the steel (lessons the RC number). Still not the entire blank, but the surface of the bore (maybe .030" deep at worst). Of course that will increase the wear. gary [/QUOTE]
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.243 Barrel Life and Cryogenics
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