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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Why I think the Satterlee and Audette Ladder Tests Work and Why-- You Decide!
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<blockquote data-quote="Veteran" data-source="post: 2435869" data-attributes="member: 118038"><p>Yes, they do change POI, and that's the whole foundation of OCW theory. I believe OCW, Satterlee, and Audette Ladder are all related to harmonics, all of them. They all work, and are all a function of the harmonic effect of change in velocity and change in POI. The whole reasoning behind finding a velocity node either from Satterlee or from Audette ladder testing where there is </p><p>not much velocity difference or vertical target dispersion with increasing charge rate is to find that spot where the barrel exit of the bullet is occuring in some consistent muzzle position, hence an accuracy node, or small group. You are trying to find a spot where there is some foregiveness in the load charge weights vs. the group size. Ie, you can be 0.1 or .2 off and there is a window where it won't matter much as to your group size. Now the POI almost always will vary some around your aim point as you go up in charge. But, the group size may not vary much when you are in a node. </p><p></p><p>I now have a tuner on my .338 LM and before that I had a big ol heavy shaft collar on it that was actually on it when I shot the </p><p>velocity curve I posted on this thread. So, I am very familiar with how the POI will change as the tuner or the harmonics change the position the muzzle is pointing at bullet exit. I am still working on a final tune for my ATS tuner, but of course I am using all the same charge weights in my ammo as I try to get the tuner to give me the smallest groups and find the setting where using consistent ammo I get small groups. Once I get it tuned with consistent ammo, I will try an experiment with increasing charge weights to see what kind of curve I graph out for velocity. In theory, I would have to retune it at each charge weight increase</p><p>because that original tune was only good for that one consistent ammo to control the harmonics.</p><p></p><p>If you did not read this link, please do. I think it says the same thing I am saying but in 1997.</p><p></p><p><a href="https://2poqx8tjzgi65olp24je4x4n-wpengine.netdna-ssl.com/wp-content/uploads/2012/07/incremental-load-development-method.pdf" target="_blank">https://2poqx8tjzgi65olp24je4x4n-wpengine.netdna-ssl.com/wp-content/uploads/2012/07/incremental-load-development-method.pdf </a></p><p></p><p>I have seen flat spots and even lower velocities on my velocity curves with 26 inch bbl on .338 LM and 28 inch barrel on my .300 WM. So, I'm not shooting short barrels either. (You may have some 30 inch plus bull barrels) I do think its possible that with really short fat barrels where harmonics do not come into play much you will not see this kind of effect, because on a short 20 inch bull barrel the round is gone before harmonics can play into it much and through FEA model analysis Varmintal has documented on his web site you don't see as much harmonic impact on bull barrels or on barrels which are shorter than 22 inches in specific. So, if you are shooting short bull barrels, you may never see a Satterlee curve hump over. The skinny pencil sporter barrels may show these effects magnified precisely because they are more vulnerable to harmonics. </p><p></p><p>So, I can believe you haven't seen it or experienced it yourself depending on what set up you are shooting, but using slower powders with slow burn rates, and loading to higher charge weights or even compressed loads with slower powders, in longer barrels, where there is time for harmonics waves to move up and down the barrel prior to bullet exit, I believe increases the odds you will see this type behaviour.</p></blockquote><p></p>
[QUOTE="Veteran, post: 2435869, member: 118038"] Yes, they do change POI, and that's the whole foundation of OCW theory. I believe OCW, Satterlee, and Audette Ladder are all related to harmonics, all of them. They all work, and are all a function of the harmonic effect of change in velocity and change in POI. The whole reasoning behind finding a velocity node either from Satterlee or from Audette ladder testing where there is not much velocity difference or vertical target dispersion with increasing charge rate is to find that spot where the barrel exit of the bullet is occuring in some consistent muzzle position, hence an accuracy node, or small group. You are trying to find a spot where there is some foregiveness in the load charge weights vs. the group size. Ie, you can be 0.1 or .2 off and there is a window where it won't matter much as to your group size. Now the POI almost always will vary some around your aim point as you go up in charge. But, the group size may not vary much when you are in a node. I now have a tuner on my .338 LM and before that I had a big ol heavy shaft collar on it that was actually on it when I shot the velocity curve I posted on this thread. So, I am very familiar with how the POI will change as the tuner or the harmonics change the position the muzzle is pointing at bullet exit. I am still working on a final tune for my ATS tuner, but of course I am using all the same charge weights in my ammo as I try to get the tuner to give me the smallest groups and find the setting where using consistent ammo I get small groups. Once I get it tuned with consistent ammo, I will try an experiment with increasing charge weights to see what kind of curve I graph out for velocity. In theory, I would have to retune it at each charge weight increase because that original tune was only good for that one consistent ammo to control the harmonics. If you did not read this link, please do. I think it says the same thing I am saying but in 1997. [URL='https://2poqx8tjzgi65olp24je4x4n-wpengine.netdna-ssl.com/wp-content/uploads/2012/07/incremental-load-development-method.pdf']https://2poqx8tjzgi65olp24je4x4n-wpengine.netdna-ssl.com/wp-content/uploads/2012/07/incremental-load-development-method.pdf [/URL] I have seen flat spots and even lower velocities on my velocity curves with 26 inch bbl on .338 LM and 28 inch barrel on my .300 WM. So, I'm not shooting short barrels either. (You may have some 30 inch plus bull barrels) I do think its possible that with really short fat barrels where harmonics do not come into play much you will not see this kind of effect, because on a short 20 inch bull barrel the round is gone before harmonics can play into it much and through FEA model analysis Varmintal has documented on his web site you don't see as much harmonic impact on bull barrels or on barrels which are shorter than 22 inches in specific. So, if you are shooting short bull barrels, you may never see a Satterlee curve hump over. The skinny pencil sporter barrels may show these effects magnified precisely because they are more vulnerable to harmonics. So, I can believe you haven't seen it or experienced it yourself depending on what set up you are shooting, but using slower powders with slow burn rates, and loading to higher charge weights or even compressed loads with slower powders, in longer barrels, where there is time for harmonics waves to move up and down the barrel prior to bullet exit, I believe increases the odds you will see this type behaviour. [/QUOTE]
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Why I think the Satterlee and Audette Ladder Tests Work and Why-- You Decide!
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