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Rifles, Reloading, Optics, Equipment
Reloading
Seating bullet depth
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<blockquote data-quote="boomtube" data-source="post: 928923" data-attributes="member: 9215"><p>"<em>Ok so 100 years ago the necks on the cases were softer so they really had no choice but to seat the bullet deep but now the necks aren't as soft as a matter of fact they are harder which started people experimenting with not seating the bullet as deep until it got to the point to were some people are touching the lands or are off the lands .002 Some guns may like it close and we can do it now without the worries of the bullet falling out of the case while in you pocket. So there is no better way to find bullet seating depth than trying different depths...And now we can extended out up to 1/3 of the diameter of the caliber or can be seated in the neck the full length of the case neck or even compressed loads if your gun likes that. It's the guns decision...Is that about right</em>???"</p><p> </p><p>Exactly. Seating depth, as such, isn't the issue so it's not a question of some magic book seating depth or any rule of thumb; as handloaders we should be loading for best performance and that includes seating! The max length question is what's practical as the longest for YOUR normal handling/feeding AND for your own magazine and chamber length. Within that max, it's up to your rig and your load for what actually works and shoots best. </p><p> </p><p>IME, most factory rifles and common (off the shelf) bullets shoot best with a jump between maybe 20 and 60 thou. "Most" means not all, some like no jump, some like even more jump than 60 thou; there's absolutely no way to guess and changing bullets will require another series of tests because there's no consistancy to it. </p><p> </p><p>As long as we're into this, I doubt that seating into the lands does much for centering a bullet into the bore, SAAMI chambers have too mich slack for displacing the rest of the case off axis for just centering the ogive to do much for alignment. Instead, I believe the real effect from seating depth is controlling the initial powder burning curve sufficent to affect how the barrel harmonics work out. For rifles, seating long greatly accelerates the initial start pressure:time slope of the burn; seating deeper slows that initial burn rate and reduces peak pressure. Therefore, tuning a hand load requires finding the correct powder charge for the best burn for your rig and load AND seating then tweeks the initial and peak burn. </p><p> </p><p>Contrary to another "conventional wisdom" accuracy rule of thumb, I've found that loading down from max pressure does not automatically improve accuracy UNLESS the chosen powder burn rate is too fast. Accuracy counts but so does speed, if I had wanted a .223 instead of a .22-250 or a .30-06 instead of a .300 Win that's what I would have bought! All powders burn most consistantly within a fairly narrow pressure range. The ideal powder and charge is one that reaches the design pressure with a small air space left (i.e., a high loading density). If I can't find an accurate high density load for a powder at or very near normal top velocity for my cartridge and bullet weight I change powders until I do.</p><p> </p><p>Last thoight; being outside the normal pressure range is hazardous because powder burn rates get squirrelly from one round to the next when the pressure is either too low or too high. Meaning an overload that was 'safe' a moment ago just may not be safe the next time it's fired.</p></blockquote><p></p>
[QUOTE="boomtube, post: 928923, member: 9215"] "[I]Ok so 100 years ago the necks on the cases were softer so they really had no choice but to seat the bullet deep but now the necks aren't as soft as a matter of fact they are harder which started people experimenting with not seating the bullet as deep until it got to the point to were some people are touching the lands or are off the lands .002 Some guns may like it close and we can do it now without the worries of the bullet falling out of the case while in you pocket. So there is no better way to find bullet seating depth than trying different depths...And now we can extended out up to 1/3 of the diameter of the caliber or can be seated in the neck the full length of the case neck or even compressed loads if your gun likes that. It's the guns decision...Is that about right[/I]???" Exactly. Seating depth, as such, isn't the issue so it's not a question of some magic book seating depth or any rule of thumb; as handloaders we should be loading for best performance and that includes seating! The max length question is what's practical as the longest for YOUR normal handling/feeding AND for your own magazine and chamber length. Within that max, it's up to your rig and your load for what actually works and shoots best. IME, most factory rifles and common (off the shelf) bullets shoot best with a jump between maybe 20 and 60 thou. "Most" means not all, some like no jump, some like even more jump than 60 thou; there's absolutely no way to guess and changing bullets will require another series of tests because there's no consistancy to it. As long as we're into this, I doubt that seating into the lands does much for centering a bullet into the bore, SAAMI chambers have too mich slack for displacing the rest of the case off axis for just centering the ogive to do much for alignment. Instead, I believe the real effect from seating depth is controlling the initial powder burning curve sufficent to affect how the barrel harmonics work out. For rifles, seating long greatly accelerates the initial start pressure:time slope of the burn; seating deeper slows that initial burn rate and reduces peak pressure. Therefore, tuning a hand load requires finding the correct powder charge for the best burn for your rig and load AND seating then tweeks the initial and peak burn. Contrary to another "conventional wisdom" accuracy rule of thumb, I've found that loading down from max pressure does not automatically improve accuracy UNLESS the chosen powder burn rate is too fast. Accuracy counts but so does speed, if I had wanted a .223 instead of a .22-250 or a .30-06 instead of a .300 Win that's what I would have bought! All powders burn most consistantly within a fairly narrow pressure range. The ideal powder and charge is one that reaches the design pressure with a small air space left (i.e., a high loading density). If I can't find an accurate high density load for a powder at or very near normal top velocity for my cartridge and bullet weight I change powders until I do. Last thoight; being outside the normal pressure range is hazardous because powder burn rates get squirrelly from one round to the next when the pressure is either too low or too high. Meaning an overload that was 'safe' a moment ago just may not be safe the next time it's fired. [/QUOTE]
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Seating bullet depth
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