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Rifles, Reloading, Optics, Equipment
Reloading
Determining Precision COALs
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<blockquote data-quote="JakeC" data-source="post: 2197631" data-attributes="member: 115819"><p>With my last barrel, a 6.5 creedmoor, I tried everything from lands minus .005 to minus .030. I found accurate spots throughout that range but when I was at .015 or less it was a lot more susceptible to pressure variations due to cleanliness, temperature, etc. And it was just fussier. Accurate until it wasn't. When I settled back to .025 (from original, who knows where the lands were at 800 rounds) I found I could shoot just as accurately for longer and with better primer pocket life.</p><p></p><p>In all these cases, at least in my gun, I was seeing early pressure signs WAY lower than published max. Like 3 grains lower. I blew a primer when I was within 1.5 grains once. I know there was a lot going into that, including the design of that case, but I'm sure being .005 off was a part of this. The new cartridge does not seem to care much about jump at all. I'm still in preliminary testing but my mag length minus wiggle room leaves me 90 thousandths off the lands with hornady ELDM and Accubond LR. When pressure testing the ELDM 180 was at 1.1 and 1.2 moa across 5 grains with two different powders. The ABLR 168 was similar after using it to sight in. The 175 ELDx was at only .030 and it shot 2+ moa, go figure. I'm sure things will get more complicated, but I was pleased and surprised by the results.</p><p></p><p>As far as HOW I went about testing and finding good lengths: with the creed I only had basic rcbs dies from cabelas, and no comparator. I was also shooting mostly matchkings which had a pretty variable length on the tip, so my COAL measurements were very rough. I'd paw through and find enough similar length pills to have them be the benchmarks for their seating groups, then I'd load two or three groups' worth at increments of 5 thou. I'd use the benchmarks to set the die and then use any random bullet out of the box for the rest of the shots that length. I'd assume that the ".020" group was 17-23 thou off, and the 25 was 22-28. It was a comically hobo setup (a Lee hand press to boot!) but by the time I was done I had 3 bullets and two powders I could reliably shoot inside a quarter, and one combo I could confidently hit a skittle with on a calm day. I'm laughing as I write because I shot SO MUCH extra components doing it this way but it taught me 1) to REALLY appreciate the "grownup" press and dies I now have, and 2) an accurate load that is fussy to within a couple thousandths (or kernels of powder) is a bad load. And for me, getting closer than 20 thousandths made everything a lot fussier. Doesn't mean you shouldn't try it just to see.</p><p></p><p>With the new setup and new cartridge (7 SAUM) I'll be doing it pretty much the same way, but I'll be able to do much smaller strings at smaller increments, and doe to an oversight I'll be starting from .090 off not .020. Right around the time I came to this conclusion in budgeting my new barrel Erik Cortina published the videos people have already mentioned. He's super helpful and fun to listen to if you haven't yet.</p><p></p><p>I'm not saying you shouldn't desire to be close, and people intimate with the WM have a lot of great reasons to try to maximize length. Seating the new long pills at the top of the shoulder is one perfect reason. Fitting more powder is another one if that's your thing. I'm just saying that after shooting a fair bit I got into reloading for precision all at once like you did and with similar goals, and I spent too much time assuming that my best load HAD to be somewhere under 15 thousandths off the lands based on hearing a little here and there.</p><p></p><p>Sorry I didn't realize this was getting long but I wanted to share since I was where you are just a couple years ago and decided, on purpose, to do things the hard way to see what I could accomplish. I would have broken my arm and my budget if I'd shot that much out of your gun though! Best of luck.</p></blockquote><p></p>
[QUOTE="JakeC, post: 2197631, member: 115819"] With my last barrel, a 6.5 creedmoor, I tried everything from lands minus .005 to minus .030. I found accurate spots throughout that range but when I was at .015 or less it was a lot more susceptible to pressure variations due to cleanliness, temperature, etc. And it was just fussier. Accurate until it wasn't. When I settled back to .025 (from original, who knows where the lands were at 800 rounds) I found I could shoot just as accurately for longer and with better primer pocket life. In all these cases, at least in my gun, I was seeing early pressure signs WAY lower than published max. Like 3 grains lower. I blew a primer when I was within 1.5 grains once. I know there was a lot going into that, including the design of that case, but I'm sure being .005 off was a part of this. The new cartridge does not seem to care much about jump at all. I'm still in preliminary testing but my mag length minus wiggle room leaves me 90 thousandths off the lands with hornady ELDM and Accubond LR. When pressure testing the ELDM 180 was at 1.1 and 1.2 moa across 5 grains with two different powders. The ABLR 168 was similar after using it to sight in. The 175 ELDx was at only .030 and it shot 2+ moa, go figure. I'm sure things will get more complicated, but I was pleased and surprised by the results. As far as HOW I went about testing and finding good lengths: with the creed I only had basic rcbs dies from cabelas, and no comparator. I was also shooting mostly matchkings which had a pretty variable length on the tip, so my COAL measurements were very rough. I'd paw through and find enough similar length pills to have them be the benchmarks for their seating groups, then I'd load two or three groups' worth at increments of 5 thou. I'd use the benchmarks to set the die and then use any random bullet out of the box for the rest of the shots that length. I'd assume that the ".020" group was 17-23 thou off, and the 25 was 22-28. It was a comically hobo setup (a Lee hand press to boot!) but by the time I was done I had 3 bullets and two powders I could reliably shoot inside a quarter, and one combo I could confidently hit a skittle with on a calm day. I'm laughing as I write because I shot SO MUCH extra components doing it this way but it taught me 1) to REALLY appreciate the "grownup" press and dies I now have, and 2) an accurate load that is fussy to within a couple thousandths (or kernels of powder) is a bad load. And for me, getting closer than 20 thousandths made everything a lot fussier. Doesn't mean you shouldn't try it just to see. With the new setup and new cartridge (7 SAUM) I'll be doing it pretty much the same way, but I'll be able to do much smaller strings at smaller increments, and doe to an oversight I'll be starting from .090 off not .020. Right around the time I came to this conclusion in budgeting my new barrel Erik Cortina published the videos people have already mentioned. He's super helpful and fun to listen to if you haven't yet. I'm not saying you shouldn't desire to be close, and people intimate with the WM have a lot of great reasons to try to maximize length. Seating the new long pills at the top of the shoulder is one perfect reason. Fitting more powder is another one if that's your thing. I'm just saying that after shooting a fair bit I got into reloading for precision all at once like you did and with similar goals, and I spent too much time assuming that my best load HAD to be somewhere under 15 thousandths off the lands based on hearing a little here and there. Sorry I didn't realize this was getting long but I wanted to share since I was where you are just a couple years ago and decided, on purpose, to do things the hard way to see what I could accomplish. I would have broken my arm and my budget if I'd shot that much out of your gun though! Best of luck. [/QUOTE]
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