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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Using Quick Load for Optimum Barrel Timing and OCW Node Matches
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<blockquote data-quote="Veteran" data-source="post: 2447121" data-attributes="member: 118038"><p>In that thread, the OP of that thread posits the following.</p><p></p><p><em><span style="color: rgb(85, 57, 130)">I have come to the conclusion that the OBT nodes are independent of barrel length and a function of muzzle velocity only.</span></em></p><p> <em><span style="color: rgb(85, 57, 130)">For example, 20", 22", and 24" all have separate ideal recommended optimum barrel times, but they all occur at the same muzzle velocity for a given "node". Anyone else come to the same conclusion based on your data analysis? </span></em></p><p></p><p><span style="color: rgb(85, 57, 130)">I believe its not possible if you are following the theory as Chris Long has derived it. Below is attached a table in pdf of Barrel times in milli seconds that match each of his 7 nodes for different barrel lengths. If you have a 16, 18, 20, 22, 24 inch barrel, there is a different time listed for any given node and they are all different from one another and unique. Each one of these barrel times represents a different velocity, because the velocity decreases from node 1 to node 7 or increases as you go from node 7 towards node 1. I have never been able to achieve a node 5 with my 26 inch bbl .338 LM because to get to node 5, I'd have to shoot a dangerous way over pressured load. So, I focus on matching node 6 for my barrel. I can achieve node 7 because its a slower load too. The velocities all have to be different at each of these nodes because the barrel times are different, and barrel time is just a proxy for velocity. You have to reduce charge weight to slow the bullet down if you are going from say node 6 to node 7. </span></p><p><span style="color: rgb(85, 57, 130)">So that also implies that lower charge weights, longer time of bullet exit is at a lower velocity.</span></p><p><span style="color: rgb(85, 57, 130)"></span></p><p><span style="color: rgb(85, 57, 130)">Now, a load that was tuned for a 22 or 24 inch bbl may still shoot fine in a 16, 18, or 20 inch bbl, because the shorter the bbl, the </span></p><p><span style="color: rgb(85, 57, 130)">less harmonics comes into play, especially with high velocity loads. The bullet can be gone before the harmonics whip the bbl around in a shorter bbl. rifle. Thats why we don't even worry about harmonics in a pistol for example.</span></p><p><span style="color: rgb(85, 57, 130)"></span></p><p><span style="color: rgb(85, 57, 130)">Also if you look at Haral's work here at this link below and go down to his optimum barrel length experiment you will see he finds the optimum bbl length to get rid of harmonics for the most part is 17 inches. Even at 22 inches, the curve isn't going up that much worse. </span></p><p><span style="color: rgb(85, 57, 130)"></span></p><p><span style="color: rgb(85, 57, 130)">Go Alllllll the way to the bottom of this link, and you will find the work on optimum bbl. length.</span></p><p><span style="color: rgb(85, 57, 130)"></span></p><p><span style="color: rgb(85, 57, 130)"><strong>Barrel Length vs Accuracy & Muzzle Velocity</strong></span></p><p><span style="color: rgb(85, 57, 130)"><strong></strong></span></p><p><span style="color: rgb(85, 57, 130)"><strong>[URL unfurl="true"]https://wwws.varmintal.com/alite.htm[/URL]</strong></span></p></blockquote><p></p>
[QUOTE="Veteran, post: 2447121, member: 118038"] In that thread, the OP of that thread posits the following. [I][COLOR=rgb(85, 57, 130)]I have come to the conclusion that the OBT nodes are independent of barrel length and a function of muzzle velocity only. For example, 20", 22", and 24" all have separate ideal recommended optimum barrel times, but they all occur at the same muzzle velocity for a given "node". Anyone else come to the same conclusion based on your data analysis? [/COLOR][/I] [COLOR=rgb(85, 57, 130)]I believe its not possible if you are following the theory as Chris Long has derived it. Below is attached a table in pdf of Barrel times in milli seconds that match each of his 7 nodes for different barrel lengths. If you have a 16, 18, 20, 22, 24 inch barrel, there is a different time listed for any given node and they are all different from one another and unique. Each one of these barrel times represents a different velocity, because the velocity decreases from node 1 to node 7 or increases as you go from node 7 towards node 1. I have never been able to achieve a node 5 with my 26 inch bbl .338 LM because to get to node 5, I'd have to shoot a dangerous way over pressured load. So, I focus on matching node 6 for my barrel. I can achieve node 7 because its a slower load too. The velocities all have to be different at each of these nodes because the barrel times are different, and barrel time is just a proxy for velocity. You have to reduce charge weight to slow the bullet down if you are going from say node 6 to node 7. So that also implies that lower charge weights, longer time of bullet exit is at a lower velocity. Now, a load that was tuned for a 22 or 24 inch bbl may still shoot fine in a 16, 18, or 20 inch bbl, because the shorter the bbl, the less harmonics comes into play, especially with high velocity loads. The bullet can be gone before the harmonics whip the bbl around in a shorter bbl. rifle. Thats why we don't even worry about harmonics in a pistol for example. Also if you look at Haral's work here at this link below and go down to his optimum barrel length experiment you will see he finds the optimum bbl length to get rid of harmonics for the most part is 17 inches. Even at 22 inches, the curve isn't going up that much worse. Go Alllllll the way to the bottom of this link, and you will find the work on optimum bbl. length. [B]Barrel Length vs Accuracy & Muzzle Velocity [URL unfurl="true"]https://wwws.varmintal.com/alite.htm[/URL][/B][/COLOR] [/QUOTE]
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Using Quick Load for Optimum Barrel Timing and OCW Node Matches
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