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Rifles, Reloading, Optics, Equipment
Reloading
Case web expansion help
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<blockquote data-quote="bigedp51" data-source="post: 1315600" data-attributes="member: 28965"><p><span style="font-size: 15px"><span style="font-size: 10px">Below from the Hodgdon powder website.</span><strong></strong></span></p><p><span style="font-size: 15px"><strong></strong></span></p><p><span style="font-size: 15px"><strong>Simple Trick for Monitoring Pressure of Your Rifle Reloads</strong></span></p><p><span style="font-size: 15px"><span style="font-size: 10px"><u><u><u><u><u><u><u><u><u><u><u><u><a href="http://www.hodgdonreloading.com/reloading-education/tips-and-tricks/simple-trick-monitoring-pressure-your-rifle-reloads" target="_blank">Simple Trick for Monitoring Pressure of Your Rifle Reloads | Hodgdon Reloading</a></u></u></u></u></u></u></u></u></u></u></u></u></span></span></p><p><span style="font-size: 15px"><span style="font-size: 10px"></span></span></p><p> <em>One of the first rules of handloading is to always follow the approved reload data. The cautious reloader gradually works up to approved maximum loads to ensure his particular gun does not show pressure signs. Generally this is visual observation of the fired shell case head and primer. There is another slick way to check for pressure signs if you are interested.</em></p><p><em></em></p><p> <em>Using a blade micrometer that measures in ten thousandths (.0001"), new, unfired cases can be gauged before and after firing to determine reasonably accurate maximum loads. Micrometers measuring in thousandths (.001") are insufficiently accurate to perform these measurements, and should not be used. Previously fired cases cannot be used accurately due to various levels of brass hardening.<strong> <span style="font-size: 12px">Measurement is taken just ahead of the extractor groove on the case head and must be taken at the same place on the case before and after firing</span>.</strong> By placing a small mark on the case head – entering the cartridge in the chamber with mark at 12 o'clock – a consistently accurate measurement can be taken with each firing. </em></p><p><em></em></p><p> <em>Lower pressure rounds, like the .30-30 Winchester, usually yield maximum pressures at .0003"-.0004" expansion. Modern cartridges, like the .223 Remington, will show maximum pressure at .0004"-.0005", while .308 Winchester, .270 Winchester, etc., typically yield .0005"-.0006" expansion at max pressure. Magnums, like the .300 Winchester Magnum, show maximums at .0006"-.0007" expansion, and should be measured on the belt. </em></p><p><em></em></p><p> <em>In conjunction with these measurements, case head signs of pressure should be monitored as well. These signs include very flat primers, slightly cratered primers, ejector marks on the case head, and stiff extraction. All these case head signs indicate high pressure, and loads should be reduced until these signs disappear.</em></p><p><em></em></p><p> <em>As always, start with the beginning load listed, and cautiously work up to the maximum shown for that set of components, using the methods listed herein.</em></p><p><em></em></p><p></p><p>As posted before the two cases below were fired in the same .303 British No.4 Enfield rifle, noted for their larger diameter chambers and longer headspace settings. The expansion ring on the Greek HXP case is more pronounced because of the cases smaller base diameter and thinner case walls. Measuring this part of the case means nothing because as you can see the Prvi Parizan case is a larger diameter and .010 thicker in this area. Meaning smaller diameter cases with thinner case walls will expand more than larger diameter and thicker cases. </p><p></p><p>Again this is why I buy bulk Lake City cases that have harder brass in the base and thicker flash hole web that adds radial strength to the base just above the extractor groove.</p><p> </p><p><img src="http://i.imgur.com/eM3H3ls.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>Part of the early jamming problem with the M16 rifle was soft brass brought out in the 1968 Congressional hearings. And the cases were made harder in the base at Lake City and commercial contract ammunition made for the military. </p><p></p><p><img src="http://i.imgur.com/OujD1z7.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>The photo below came from AR15.com and shows a 2 inch rod that fits inside the case to measure flash hole web thickness. The reason for this check is because Federal cases had the thinnest flash hole web and had "MORE" base expansion causing oversized primer pockets.</p><p></p><p> <img src="http://i.imgur.com/POsazjb.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>Base expansion just above the extractor groove will show you that you are over stressing the brass beyond its elastic limits. Meaning over sized primer pockets that can cause gas leakage and a etched bolt face.</p><p></p><p>And now the funny part, the person who posted the photo below said he didn't worry about loose primer pockets. And he would just replace the bolt when it became bad enough. <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:" /></p><p></p><p></p><p><img src="http://i.imgur.com/VMkEdYr.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>Bottom line measuring higher up the case where the case expands to meet the chamber walls means nothing. All this tells you is how much smaller in diameter the case is than chamber diameter. And measuring just above the extractor groove will tell you if you are over stressing the base of the case from more chamber pressure than the base can take.</p></blockquote><p></p>
[QUOTE="bigedp51, post: 1315600, member: 28965"] [SIZE=4][SIZE=2]Below from the Hodgdon powder website.[/SIZE][B] Simple Trick for Monitoring Pressure of Your Rifle Reloads[/B] [SIZE=2][U][U][U][U][U][U][U][U][U][U][U][U][URL="http://www.hodgdonreloading.com/reloading-education/tips-and-tricks/simple-trick-monitoring-pressure-your-rifle-reloads"]Simple Trick for Monitoring Pressure of Your Rifle Reloads | Hodgdon Reloading[/URL][/U][/U][/U][/U][/U][/U][/U][/U][/U][/U][/U][/U] [/SIZE][/SIZE] [I]One of the first rules of handloading is to always follow the approved reload data. The cautious reloader gradually works up to approved maximum loads to ensure his particular gun does not show pressure signs. Generally this is visual observation of the fired shell case head and primer. There is another slick way to check for pressure signs if you are interested. Using a blade micrometer that measures in ten thousandths (.0001"), new, unfired cases can be gauged before and after firing to determine reasonably accurate maximum loads. Micrometers measuring in thousandths (.001") are insufficiently accurate to perform these measurements, and should not be used. Previously fired cases cannot be used accurately due to various levels of brass hardening.[B] [SIZE=3]Measurement is taken just ahead of the extractor groove on the case head and must be taken at the same place on the case before and after firing[/SIZE].[/B] By placing a small mark on the case head – entering the cartridge in the chamber with mark at 12 o’clock – a consistently accurate measurement can be taken with each firing. Lower pressure rounds, like the .30-30 Winchester, usually yield maximum pressures at .0003"-.0004" expansion. Modern cartridges, like the .223 Remington, will show maximum pressure at .0004"-.0005", while .308 Winchester, .270 Winchester, etc., typically yield .0005"-.0006" expansion at max pressure. Magnums, like the .300 Winchester Magnum, show maximums at .0006”-.0007” expansion, and should be measured on the belt. In conjunction with these measurements, case head signs of pressure should be monitored as well. These signs include very flat primers, slightly cratered primers, ejector marks on the case head, and stiff extraction. All these case head signs indicate high pressure, and loads should be reduced until these signs disappear. As always, start with the beginning load listed, and cautiously work up to the maximum shown for that set of components, using the methods listed herein. [/I] As posted before the two cases below were fired in the same .303 British No.4 Enfield rifle, noted for their larger diameter chambers and longer headspace settings. The expansion ring on the Greek HXP case is more pronounced because of the cases smaller base diameter and thinner case walls. Measuring this part of the case means nothing because as you can see the Prvi Parizan case is a larger diameter and .010 thicker in this area. Meaning smaller diameter cases with thinner case walls will expand more than larger diameter and thicker cases. Again this is why I buy bulk Lake City cases that have harder brass in the base and thicker flash hole web that adds radial strength to the base just above the extractor groove. [IMG]http://i.imgur.com/eM3H3ls.jpg[/IMG] Part of the early jamming problem with the M16 rifle was soft brass brought out in the 1968 Congressional hearings. And the cases were made harder in the base at Lake City and commercial contract ammunition made for the military. [IMG]http://i.imgur.com/OujD1z7.jpg[/IMG] The photo below came from AR15.com and shows a 2 inch rod that fits inside the case to measure flash hole web thickness. The reason for this check is because Federal cases had the thinnest flash hole web and had "MORE" base expansion causing oversized primer pockets. [IMG]http://i.imgur.com/POsazjb.jpg[/IMG] Base expansion just above the extractor groove will show you that you are over stressing the brass beyond its elastic limits. Meaning over sized primer pockets that can cause gas leakage and a etched bolt face. And now the funny part, the person who posted the photo below said he didn't worry about loose primer pockets. And he would just replace the bolt when it became bad enough. :rolleyes: [IMG]http://i.imgur.com/VMkEdYr.jpg[/IMG] Bottom line measuring higher up the case where the case expands to meet the chamber walls means nothing. All this tells you is how much smaller in diameter the case is than chamber diameter. And measuring just above the extractor groove will tell you if you are over stressing the base of the case from more chamber pressure than the base can take. [/QUOTE]
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