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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Loading for a particular barrel length
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<blockquote data-quote="CPorter" data-source="post: 99201" data-attributes="member: 4952"><p>Like the other mentioned you will need to work up your own loads. That said, in general with a shorter barrel you will get lower velocities, I would guess maybe 125 fps with 6" less barrel, for the same load.</p><p></p><p>If you are a fan of the shockwave theory then the optimum barrel times change as well. 10 nodes are listed below for each barrel length.</p><p></p><p>26" 20"</p><p>0.88 0.68</p><p>0.97 0.75</p><p>1.11 0.86</p><p>1.19 0.92</p><p>1.33 1.03</p><p>1.41 1.10</p><p>1.55 1.20</p><p>1.64 1.27</p><p></p><p>To give you an idea what this means I have some data from Quickload below. Notice that the barrel time (ms column) changes from 1.31 to 1.133 as the charge goes up. According to the shock wave theory the more accurate load will be at 45.7 grains or 1.19ms barrel time. Quickload says a 20" barrel would be 240fps slower and in this case the same load would be at an accuracy node of 1.03ms</p><p></p><p></p><p></p><p>Step Fill. Charge Vel. Energy Pmax Pmuz Prop. Burnt B_Time</p><p>% % Grains fps ft.lbs psi psi % ms</p><p> </p><p>-6.6 90 42.7 3125 1518 38747 8763 95.1 1.31</p><p>-5.9 91 43.0 3147 1539 39591 8823 95.4 1.297</p><p>-5.3 91 43.3 3169 1561 40454 8881 95.7 1.284</p><p>-4.6 92 43.6 3191 1583 41336 8938 96.0 1.272</p><p>-3.9 93 43.9 3213 1605 42236 8993 96.3 1.259</p><p>-3.3 93 44.2 3235 1627 43156 9047 96.6 1.247</p><p>-2.6 94 44.5 3257 1649 44097 9099 96.9 1.235</p><p>-2 95 44.8 3279 1671 45057 9150 97.2 1.223</p><p>-1.3 95 45.1 3301 1693 46039 9198 97.4 1.212</p><p>-0.7 96 45.4 3323 1716 47042 9245 97.7 1.2</p><p>0 97 45.7 3344 1738 48067 9291 97.9 1.189</p><p>0.7 97 46.0 3366 1761 49115 9335 98.1 1.177</p><p>1.3 98 46.3 3388 1784 50186 9376 98.3 1.166</p><p>2 98 46.6 3409 1807 51280 9416 98.5 1.155</p><p>2.6 99 46.9 3431 1830 52398 9455 98.7 1.144</p><p>3.3 100 47.2 3452 1853 53542 9491 98.9 1.133</p></blockquote><p></p>
[QUOTE="CPorter, post: 99201, member: 4952"] Like the other mentioned you will need to work up your own loads. That said, in general with a shorter barrel you will get lower velocities, I would guess maybe 125 fps with 6" less barrel, for the same load. If you are a fan of the shockwave theory then the optimum barrel times change as well. 10 nodes are listed below for each barrel length. 26" 20" 0.88 0.68 0.97 0.75 1.11 0.86 1.19 0.92 1.33 1.03 1.41 1.10 1.55 1.20 1.64 1.27 To give you an idea what this means I have some data from Quickload below. Notice that the barrel time (ms column) changes from 1.31 to 1.133 as the charge goes up. According to the shock wave theory the more accurate load will be at 45.7 grains or 1.19ms barrel time. Quickload says a 20" barrel would be 240fps slower and in this case the same load would be at an accuracy node of 1.03ms Step Fill. Charge Vel. Energy Pmax Pmuz Prop. Burnt B_Time % % Grains fps ft.lbs psi psi % ms -6.6 90 42.7 3125 1518 38747 8763 95.1 1.31 -5.9 91 43.0 3147 1539 39591 8823 95.4 1.297 -5.3 91 43.3 3169 1561 40454 8881 95.7 1.284 -4.6 92 43.6 3191 1583 41336 8938 96.0 1.272 -3.9 93 43.9 3213 1605 42236 8993 96.3 1.259 -3.3 93 44.2 3235 1627 43156 9047 96.6 1.247 -2.6 94 44.5 3257 1649 44097 9099 96.9 1.235 -2 95 44.8 3279 1671 45057 9150 97.2 1.223 -1.3 95 45.1 3301 1693 46039 9198 97.4 1.212 -0.7 96 45.4 3323 1716 47042 9245 97.7 1.2 0 97 45.7 3344 1738 48067 9291 97.9 1.189 0.7 97 46.0 3366 1761 49115 9335 98.1 1.177 1.3 98 46.3 3388 1784 50186 9376 98.3 1.166 2 98 46.6 3409 1807 51280 9416 98.5 1.155 2.6 99 46.9 3431 1830 52398 9455 98.7 1.144 3.3 100 47.2 3452 1853 53542 9491 98.9 1.133 [/QUOTE]
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