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Rifles, Reloading, Optics, Equipment
Reloading
Head spacing and seating depth!
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<blockquote data-quote="boomtube" data-source="post: 753356" data-attributes="member: 9215"><p>Most of us make both things far more difficult to grasp than they should be. OAL and headspace are totally seperate issues.</p><p> </p><p>How and where headspace is measured hardly matters, all it amounts to is the room in the chamber for the cartridge to fit. If our cases are too big in any dimension they won't chamber, usually because a bottleneck shoulder isn't pushed back far enough. If our cartridge is too small it's a sloppy fit and it will have to stretch too much for safety. Forget any definitions of headspace for rimmed or belted cases, if it has a bottle neck just adjust your sizer off the shoulder. Do your own expermentation on how far back to set your AR shoulders, if any at all. Don't 'average' anything, just set your sizer so the <u>longest sized shoulder</u> matches or is just shorter than the <u>longest fired length</u>; anything shorter will obviously fit fine. </p><p> </p><p>Rifle or pistol, the "right" OAL is one that feeds and chambers reliably without jamming the bullet into the rifling (you can't get revolver bullets into the rifling!) AND shoots best in your rig. The OAL in books isn't automatically right for anything but the gun used to develop the listed data, each of us can pick our own OAL. Find the longest length that will fit your magazine and feed, then see if the bullet jams into the lands; if it does just push the bullet deeper until it doesn't. Start your load development close to (but not in) the lands and find the best shooting charge. Then do range testing in groups of maybe two at first, moving back in something like 5 thou steps until you find what seems to shoot well and do more extensive tests around that point, including tweaking the powder charge a couple tenths each way.</p><p> </p><p>The hyperventalating you see on the web about seating deeper running pressures up applies ONLY to the hot small case autoloading hand gun cartridges like the 9 and 10mm/.40 that are high pressure rounds using very fast burning powders. It doesn't apply to rifles and hardly has any meaning for lower pressure autos like the .45 ACP or revolver cartridges.</p><p> </p><p>Good luck!</p></blockquote><p></p>
[QUOTE="boomtube, post: 753356, member: 9215"] Most of us make both things far more difficult to grasp than they should be. OAL and headspace are totally seperate issues. How and where headspace is measured hardly matters, all it amounts to is the room in the chamber for the cartridge to fit. If our cases are too big in any dimension they won't chamber, usually because a bottleneck shoulder isn't pushed back far enough. If our cartridge is too small it's a sloppy fit and it will have to stretch too much for safety. Forget any definitions of headspace for rimmed or belted cases, if it has a bottle neck just adjust your sizer off the shoulder. Do your own expermentation on how far back to set your AR shoulders, if any at all. Don't 'average' anything, just set your sizer so the [U]longest sized shoulder[/U] matches or is just shorter than the [U]longest fired length[/U]; anything shorter will obviously fit fine. Rifle or pistol, the "right" OAL is one that feeds and chambers reliably without jamming the bullet into the rifling (you can't get revolver bullets into the rifling!) AND shoots best in your rig. The OAL in books isn't automatically right for anything but the gun used to develop the listed data, each of us can pick our own OAL. Find the longest length that will fit your magazine and feed, then see if the bullet jams into the lands; if it does just push the bullet deeper until it doesn't. Start your load development close to (but not in) the lands and find the best shooting charge. Then do range testing in groups of maybe two at first, moving back in something like 5 thou steps until you find what seems to shoot well and do more extensive tests around that point, including tweaking the powder charge a couple tenths each way. The hyperventalating you see on the web about seating deeper running pressures up applies ONLY to the hot small case autoloading hand gun cartridges like the 9 and 10mm/.40 that are high pressure rounds using very fast burning powders. It doesn't apply to rifles and hardly has any meaning for lower pressure autos like the .45 ACP or revolver cartridges. Good luck! [/QUOTE]
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Head spacing and seating depth!
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