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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
280 rem trajectory doesnt seem right
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<blockquote data-quote="BryanLitz" data-source="post: 712445" data-attributes="member: 7848"><p>If you output your chart in small enough range increments, you can tell if it's rising or falling at the 100 yard zero. Consider the output below in 10 yard increments, you can see that the trajectory rises slightly above the line of sight before 100 yards, then falls down to the zero point at 100 yards, and continues to fall beyond that. With a faster MV, and a higher sight height, the bullet could very well still be rising at 100 yards, which the drop chart would show if the range increment is small enough.</p><p></p><p>[code]</p><p> Range Velocity Energy Trajectory TOF Drift</p><p> (yards) (fps) (ft-lb) (inches) (sec) (inches)</p><p> 0 2600 2326 -1.50 0.0000 0.00</p><p> 10 2581 2292 -1.11 0.0116 -0.01</p><p> 20 2561 2258 -0.76 0.0232 -0.03</p><p> 30 2542 2224 -0.47 0.0350 -0.07</p><p> 40 2523 2190 -0.24 0.0469 -0.12</p><p> 50 2504 2157 -0.06 0.0588 -0.20</p><p> 60 2485 2124 0.07 0.0708 -0.28</p><p> 70 2466 2092 0.14 0.0829 -0.38</p><p> 80 2447 2060 0.15 0.0951 -0.50</p><p> 90 2428 2029 0.10 0.1075 -0.64</p><p> 100 2409 1998 -0.00 0.1199 -0.79</p><p> 110 2391 1967 -0.16 0.1324 -0.96</p><p> 120 2372 1937 -0.39 0.1450 -1.15</p><p> 130 2354 1907 -0.68 0.1576 -1.35</p><p> 140 2335 1877 -1.03 0.1704 -1.57</p><p> 150 2317 1848 -1.44 0.1833 -1.81</p><p> 160 2299 1819 -1.92 0.1963 -2.07</p><p> 170 2281 1790 -2.46 0.2094 -2.35</p><p> 180 2263 1762 -3.07 0.2226 -2.64</p><p> 190 2245 1734 -3.75 0.2360 -2.95</p><p> 200 2227 1706 -4.50 0.2494 -3.29</p><p> 210 2209 1679 -5.32 0.2629 -3.64</p><p> 220 2191 1652 -6.21 0.2765 -4.00</p><p> 230 2174 1626 -7.17 0.2903 -4.39</p><p> 240 2156 1600 -8.20 0.3041 -4.80</p><p> 250 2139 1574 -9.31 0.3181 -5.23</p><p> 260 2121 1548 -10.50 0.3322 -5.68</p><p> 270 2104 1523 -11.76 0.3464 -6.15</p><p> 280 2087 1498 -13.10 0.3607 -6.64</p><p> 290 2069 1474 -14.52 0.3751 -7.15</p><p> 300 2052 1450 -16.03 0.3897 -7.68</p><p> 310 2035 1426 -17.61 0.4044 -8.23</p><p> 320 2018 1402 -19.28 0.4192 -8.81</p><p> 330 2002 1379 -21.03 0.4341 -9.41</p><p> 340 1985 1356 -22.87 0.4491 -10.02</p><p> 350 1968 1333 -24.80 0.4643 -10.67</p><p> 360 1951 1311 -26.82 0.4796 -11.33</p><p> 370 1935 1288 -28.93 0.4951 -12.02</p><p> 380 1918 1266 -31.14 0.5106 -12.73</p><p> 390 1902 1245 -33.43 0.5263 -13.46</p><p> 400 1885 1223 -35.83 0.5422 -14.22</p><p> 410 1869 1202 -38.32 0.5582 -15.00</p><p> 420 1853 1182 -40.91 0.5743 -15.81</p><p> 430 1837 1161 -43.60 0.5905 -16.64</p><p> 440 1821 1141 -46.39 0.6070 -17.50</p><p> 450 1805 1121 -49.29 0.6235 -18.38</p><p> 460 1789 1101 -52.30 0.6402 -19.29</p><p> 470 1773 1082 -55.41 0.6570 -20.22</p><p> 480 1757 1062 -58.64 0.6740 -21.18</p><p> 490 1741 1043 -61.98 0.6912 -22.17</p><p> 500 1725 1025 -65.43 0.7085 -23.19</p><p>[/code]</p><p></p><p></p><p></p><p></p><p>The chart assumes no such thing. If you only look at the output in 100 yard increments, YOU can't tell if it's rising or falling, but the ballistics program that generated the chart *must* know the state of the bullet (rising or falling) on a continuous basis thruout the trajectory, even if it's just outputting every 100 yards.</p><p></p><p></p><p></p><p>The reason for ballistic program predictions not lining up with observed drop can almost always be attributed to inaccurate inputs. If you input accurate data into a good ballistics program, it will calculate an accurate trajectory at least over the supersonic range of the projectile. This has been documented many times. Admittedly it's difficult to get all the variables truly accurate, but if you do, the predictions are valid without correction.</p><p></p><p></p><p></p><p>You could do that. Typically I advise shorter range zeroes because it makes the zero less susceptible to conditions, wind, etc. If you want a long PBR for quick engagements, it makes sense to consider a longer range zero.</p><p></p><p>Dan,</p><p>I'm not attacking you or trying to be contrary for the fun of it. Just offering a new guy multiple perspectives to consider. No offense intended.</p><p></p><p>-Bryan</p></blockquote><p></p>
[QUOTE="BryanLitz, post: 712445, member: 7848"] If you output your chart in small enough range increments, you can tell if it's rising or falling at the 100 yard zero. Consider the output below in 10 yard increments, you can see that the trajectory rises slightly above the line of sight before 100 yards, then falls down to the zero point at 100 yards, and continues to fall beyond that. With a faster MV, and a higher sight height, the bullet could very well still be rising at 100 yards, which the drop chart would show if the range increment is small enough. [code] Range Velocity Energy Trajectory TOF Drift (yards) (fps) (ft-lb) (inches) (sec) (inches) 0 2600 2326 -1.50 0.0000 0.00 10 2581 2292 -1.11 0.0116 -0.01 20 2561 2258 -0.76 0.0232 -0.03 30 2542 2224 -0.47 0.0350 -0.07 40 2523 2190 -0.24 0.0469 -0.12 50 2504 2157 -0.06 0.0588 -0.20 60 2485 2124 0.07 0.0708 -0.28 70 2466 2092 0.14 0.0829 -0.38 80 2447 2060 0.15 0.0951 -0.50 90 2428 2029 0.10 0.1075 -0.64 100 2409 1998 -0.00 0.1199 -0.79 110 2391 1967 -0.16 0.1324 -0.96 120 2372 1937 -0.39 0.1450 -1.15 130 2354 1907 -0.68 0.1576 -1.35 140 2335 1877 -1.03 0.1704 -1.57 150 2317 1848 -1.44 0.1833 -1.81 160 2299 1819 -1.92 0.1963 -2.07 170 2281 1790 -2.46 0.2094 -2.35 180 2263 1762 -3.07 0.2226 -2.64 190 2245 1734 -3.75 0.2360 -2.95 200 2227 1706 -4.50 0.2494 -3.29 210 2209 1679 -5.32 0.2629 -3.64 220 2191 1652 -6.21 0.2765 -4.00 230 2174 1626 -7.17 0.2903 -4.39 240 2156 1600 -8.20 0.3041 -4.80 250 2139 1574 -9.31 0.3181 -5.23 260 2121 1548 -10.50 0.3322 -5.68 270 2104 1523 -11.76 0.3464 -6.15 280 2087 1498 -13.10 0.3607 -6.64 290 2069 1474 -14.52 0.3751 -7.15 300 2052 1450 -16.03 0.3897 -7.68 310 2035 1426 -17.61 0.4044 -8.23 320 2018 1402 -19.28 0.4192 -8.81 330 2002 1379 -21.03 0.4341 -9.41 340 1985 1356 -22.87 0.4491 -10.02 350 1968 1333 -24.80 0.4643 -10.67 360 1951 1311 -26.82 0.4796 -11.33 370 1935 1288 -28.93 0.4951 -12.02 380 1918 1266 -31.14 0.5106 -12.73 390 1902 1245 -33.43 0.5263 -13.46 400 1885 1223 -35.83 0.5422 -14.22 410 1869 1202 -38.32 0.5582 -15.00 420 1853 1182 -40.91 0.5743 -15.81 430 1837 1161 -43.60 0.5905 -16.64 440 1821 1141 -46.39 0.6070 -17.50 450 1805 1121 -49.29 0.6235 -18.38 460 1789 1101 -52.30 0.6402 -19.29 470 1773 1082 -55.41 0.6570 -20.22 480 1757 1062 -58.64 0.6740 -21.18 490 1741 1043 -61.98 0.6912 -22.17 500 1725 1025 -65.43 0.7085 -23.19 [/code] The chart assumes no such thing. If you only look at the output in 100 yard increments, YOU can't tell if it's rising or falling, but the ballistics program that generated the chart *must* know the state of the bullet (rising or falling) on a continuous basis thruout the trajectory, even if it's just outputting every 100 yards. The reason for ballistic program predictions not lining up with observed drop can almost always be attributed to inaccurate inputs. If you input accurate data into a good ballistics program, it will calculate an accurate trajectory at least over the supersonic range of the projectile. This has been documented many times. Admittedly it's difficult to get all the variables truly accurate, but if you do, the predictions are valid without correction. You could do that. Typically I advise shorter range zeroes because it makes the zero less susceptible to conditions, wind, etc. If you want a long PBR for quick engagements, it makes sense to consider a longer range zero. Dan, I'm not attacking you or trying to be contrary for the fun of it. Just offering a new guy multiple perspectives to consider. No offense intended. -Bryan [/QUOTE]
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280 rem trajectory doesnt seem right
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