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Rifles, Reloading, Optics, Equipment
Gunsmithing
Why is there no coatings used in rifle throats to slow erosion?
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<blockquote data-quote="royinidaho" data-source="post: 576600" data-attributes="member: 2011"><p>fly,</p><p></p><p>Read the whole thing. Good stuff. </p><p></p><p>I noted this tidbit from the report: "<span style="color: Teal">This shows that erosion resulting from the propellant gas is larger in the free flight zone compared with the center zone. This result seems natural since the pressure in the free flight zone is about double that of the center zone.</span>"</p><p></p><p>I wonder how much of this erosion is due to hot gasses or friction from powder kernels?</p><p></p><p>This finding suggests that the boys at the Ogen Depot, back in the day, were on the right track. I don't know what their objective was. I understand that their development remains in use in the 10x(5?) mm cannon shell.</p><p></p><p>Their work was with "forward ignition". Kirby did some experimenting with FI. I've ruined a few pieces of brass messing with it also. Actually not ruined, if I sleeve the drilled and threaded flash holes.<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p><p></p><p>My idea is to burn all the powder in the case. I doubt that is a possibility. After launching a few flash tubes down range barrel temperature profile definitely was affected.</p><p></p><p>Objective:</p><p></p><ul> <li data-xf-list-type="ul">Reduce throat erosion. That is, the portion of throat erosion due to sand blasting effect of unburned powder kernels under high pressure.</li> </ul><p></p><p>Results:</p><p></p><ul> <li data-xf-list-type="ul">Recoil noticeably reduced</li> <li data-xf-list-type="ul">Barrel temperature beyond the first 6 or 7 inches was lower than the chamber area.</li> <li data-xf-list-type="ul">Barrel heat flowed from the chamber area down the barrel.</li> <li data-xf-list-type="ul">Group size decreased (consistently but from an already great shooting hunting rig not enough to be worth the effort for group size reduction only.</li> </ul><p>Conclusions:</p><p></p><ul> <li data-xf-list-type="ul">RUM sized cases are too small to benefit from forward ignition. (We'll see about the 375 AM cartridge.lightbulb)</li> <li data-xf-list-type="ul">Sufficient ballistic performance, for hunting, will have to be limited to realistic chamber pressures. The best I could determine was that flash tube launches occurred only at extreme velocity/pressure which from close observation of threads in the primer pocket seemed to indicated case head expansion released the flash tube. No sheared brass was detected in flash hole threads. Threads were good and reusable throughout the experiments. (Have no idea of where the flash tubes landed. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite11" alt=":rolleyes:" title="Roll Eyes :rolleyes:" loading="lazy" data-shortname=":rolleyes:" />)</li> <li data-xf-list-type="ul">Reloading process was extended. Add flash tube removal and installation after primer removal. Not much of an effort but definitely an extra step.</li> </ul><p>Will I do additional testing. Oh, yeah! </p><p></p><p></p><p></p><p>Also, after about a dozen Upper GI roto-rooter procedures, its the throat that takes the beating.<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite8" alt=":D" title="Big Grin :D" loading="lazy" data-shortname=":D" /></p></blockquote><p></p>
[QUOTE="royinidaho, post: 576600, member: 2011"] fly, Read the whole thing. Good stuff. I noted this tidbit from the report: "[COLOR=Teal]This shows that erosion resulting from the propellant gas is larger in the free flight zone compared with the center zone. This result seems natural since the pressure in the free flight zone is about double that of the center zone.[/COLOR]" I wonder how much of this erosion is due to hot gasses or friction from powder kernels? This finding suggests that the boys at the Ogen Depot, back in the day, were on the right track. I don't know what their objective was. I understand that their development remains in use in the 10x(5?) mm cannon shell. Their work was with "forward ignition". Kirby did some experimenting with FI. I've ruined a few pieces of brass messing with it also. Actually not ruined, if I sleeve the drilled and threaded flash holes.:) My idea is to burn all the powder in the case. I doubt that is a possibility. After launching a few flash tubes down range barrel temperature profile definitely was affected. Objective: [LIST] [*]Reduce throat erosion. That is, the portion of throat erosion due to sand blasting effect of unburned powder kernels under high pressure. [/LIST] Results: [LIST] [*]Recoil noticeably reduced [*]Barrel temperature beyond the first 6 or 7 inches was lower than the chamber area. [*]Barrel heat flowed from the chamber area down the barrel. [*]Group size decreased (consistently but from an already great shooting hunting rig not enough to be worth the effort for group size reduction only. [/LIST] Conclusions: [LIST] [*]RUM sized cases are too small to benefit from forward ignition. (We'll see about the 375 AM cartridge.lightbulb) [*]Sufficient ballistic performance, for hunting, will have to be limited to realistic chamber pressures. The best I could determine was that flash tube launches occurred only at extreme velocity/pressure which from close observation of threads in the primer pocket seemed to indicated case head expansion released the flash tube. No sheared brass was detected in flash hole threads. Threads were good and reusable throughout the experiments. (Have no idea of where the flash tubes landed. :rolleyes:) [*]Reloading process was extended. Add flash tube removal and installation after primer removal. Not much of an effort but definitely an extra step. [/LIST] Will I do additional testing. Oh, yeah! Also, after about a dozen Upper GI roto-rooter procedures, its the throat that takes the beating.:D [/QUOTE]
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Why is there no coatings used in rifle throats to slow erosion?
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