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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Barrel Tuners- Muzzle Breaks- Barrel Harmonics Management
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<blockquote data-quote="Veteran" data-source="post: 2227961" data-attributes="member: 118038"><p>Yes, I agree completely. Why take a load that shoot's like pie pan size groups and try to tune that?? Do the very best job you can to get your SD and ES in single digits, Optimize your powder selection, your bullet selection, your bullet seating depth, glass bed or free float your barrel or pillar bed, get a good stock, make sure you are not shooting off concrete, hold or support the rifle the exact same way each shot, and get the best groups you can doing all the right stuff, then see if you can tune out any residual left over barrel hamonics with a tuner. I have just been amazed to learn how much deformation even a big bull barrel goes through when it is shot. I have learned that longer skinny barrels with more flex are gonna give worse problems than short fat barrels say 18 inches or less that are more rigid. </p><p></p><p>I also think that the harmonics are worse in big magnum calibers even with their bull barrels, because there is just a higher magnitude of pressure and gas wave impacting the steel. I may have ---before I started learning about harmonics in gun barrels, just chalked up larger groups on the big magnums to recoil, and they are just harder to shoot with accuracy due to recoil. But I have come to realize, there is also a significant amount of inaccuracy in big magnums that is all harmonics. I really have no excuse with my .338 Lapua Mag because it weighs 20 lbs., and the recoil is a lot less than my TC Encore .300 Win Mag. Both rifles though have a lot of harmonic issues to be managed by load development and doing all the right stuff, and then maybe using a barrel tuner to really manage the residual or left over harmonics that still exist. Now, maybe you can get a pretty low velocity, low charge load, that does not recoil as much , has less pressure and force, and the harmonics will be more manageable using just load development, but I want to be shooting at fairly flat trajectory, and at moderately high velocities, (Not max but maybe higher than factory ammo), and so I think my desire for more velocity means I am gonna possible have more issues with harmonics than if I just settle for "slow boat" kind of loads. Pea shooters don't have no harmonics.....<img class="smilie smilie--emoji" loading="lazy" alt="😄" title="Grinning face with smiling eyes :smile:" src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f604.png" data-shortname=":smile:" /></p><p></p><p>Chris Long in all of his analysis of barrel timing nodes, OBT work, has showed there are a range of velocity nodes all the way up and down the load charge weight chart for a given bullet where the harmonics may be more optimum. Some of those nodes, would require such high pressure and velocity that I can't get there without exceeding Max Pressure for my loads in either the .338 LM or the .300 WM. His theory is based on the travel time of the shock and pressure waves through steel and is a function of the barrel length. (Though I think there may be some differences in due to the weight and structure of the barrel that could also be a factor). So I generally try to shoot charges that give me an optimum barrel time that matches his nodes to try to find an optimum charge weight for a given powder and bullet. I haven't found his nodes to work exactly, but it gives me the right neighborhood to work in to do the Dan Newbury OCW, Saterlee Velocity Sill, or ladder test. I use Quickload to do all this, and I optimize Quickload to match my actual velocities to back into the actual burn rate for my particular batch or lot of powder.</p><p></p><p>Burn rate is not a constant......That's why burn rate charts are always "Relative". Even, your lot of powder if contaminated by humidity can have a change in its burn rate. So, after I get a back calculated burn rate in Quickload based on my actual velocities I will use a corrected burn rate in QuickLoad to then re-calculate the OBT charge weight using the Chris Long nodes, to see how that is matching up with my actual shooting MOA's. I do think that Varmintal's method of using FEA analysis which accounts for barrel weight, barrel taper, and barrel length is far superior to the Chris Long method, but is far too complex for me, and most other people. Few of us even has an FEA model much less could accurately manage the inputs and modeling needed to use it.</p><p>So, the best approach I have found is the combination of Chris Long's OBT method for getting a close estimate of optimal charge weight, then using the Dan Newbury OCW theory, the Saterlee Sill graph, and the ladder test to prove it out on target paper.</p><p></p><p>But, yes why tune from a pie pan size MOA load??? No, do your homework first, then make 1 ragged hole with a tuner.</p></blockquote><p></p>
[QUOTE="Veteran, post: 2227961, member: 118038"] Yes, I agree completely. Why take a load that shoot's like pie pan size groups and try to tune that?? Do the very best job you can to get your SD and ES in single digits, Optimize your powder selection, your bullet selection, your bullet seating depth, glass bed or free float your barrel or pillar bed, get a good stock, make sure you are not shooting off concrete, hold or support the rifle the exact same way each shot, and get the best groups you can doing all the right stuff, then see if you can tune out any residual left over barrel hamonics with a tuner. I have just been amazed to learn how much deformation even a big bull barrel goes through when it is shot. I have learned that longer skinny barrels with more flex are gonna give worse problems than short fat barrels say 18 inches or less that are more rigid. I also think that the harmonics are worse in big magnum calibers even with their bull barrels, because there is just a higher magnitude of pressure and gas wave impacting the steel. I may have ---before I started learning about harmonics in gun barrels, just chalked up larger groups on the big magnums to recoil, and they are just harder to shoot with accuracy due to recoil. But I have come to realize, there is also a significant amount of inaccuracy in big magnums that is all harmonics. I really have no excuse with my .338 Lapua Mag because it weighs 20 lbs., and the recoil is a lot less than my TC Encore .300 Win Mag. Both rifles though have a lot of harmonic issues to be managed by load development and doing all the right stuff, and then maybe using a barrel tuner to really manage the residual or left over harmonics that still exist. Now, maybe you can get a pretty low velocity, low charge load, that does not recoil as much , has less pressure and force, and the harmonics will be more manageable using just load development, but I want to be shooting at fairly flat trajectory, and at moderately high velocities, (Not max but maybe higher than factory ammo), and so I think my desire for more velocity means I am gonna possible have more issues with harmonics than if I just settle for "slow boat" kind of loads. Pea shooters don't have no harmonics.....😄 Chris Long in all of his analysis of barrel timing nodes, OBT work, has showed there are a range of velocity nodes all the way up and down the load charge weight chart for a given bullet where the harmonics may be more optimum. Some of those nodes, would require such high pressure and velocity that I can't get there without exceeding Max Pressure for my loads in either the .338 LM or the .300 WM. His theory is based on the travel time of the shock and pressure waves through steel and is a function of the barrel length. (Though I think there may be some differences in due to the weight and structure of the barrel that could also be a factor). So I generally try to shoot charges that give me an optimum barrel time that matches his nodes to try to find an optimum charge weight for a given powder and bullet. I haven't found his nodes to work exactly, but it gives me the right neighborhood to work in to do the Dan Newbury OCW, Saterlee Velocity Sill, or ladder test. I use Quickload to do all this, and I optimize Quickload to match my actual velocities to back into the actual burn rate for my particular batch or lot of powder. Burn rate is not a constant......That's why burn rate charts are always "Relative". Even, your lot of powder if contaminated by humidity can have a change in its burn rate. So, after I get a back calculated burn rate in Quickload based on my actual velocities I will use a corrected burn rate in QuickLoad to then re-calculate the OBT charge weight using the Chris Long nodes, to see how that is matching up with my actual shooting MOA's. I do think that Varmintal's method of using FEA analysis which accounts for barrel weight, barrel taper, and barrel length is far superior to the Chris Long method, but is far too complex for me, and most other people. Few of us even has an FEA model much less could accurately manage the inputs and modeling needed to use it. So, the best approach I have found is the combination of Chris Long's OBT method for getting a close estimate of optimal charge weight, then using the Dan Newbury OCW theory, the Saterlee Sill graph, and the ladder test to prove it out on target paper. But, yes why tune from a pie pan size MOA load??? No, do your homework first, then make 1 ragged hole with a tuner. [/QUOTE]
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