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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
powder/load recommendation 338lm/berger 250otm
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<blockquote data-quote="Bodywerks" data-source="post: 857216" data-attributes="member: 62694"><p>I'm going off of what my ballistics tables are telling me(shooter ballistics for android). So far, while accurate, the 300s aren't performing like I hoped. I'm pretty confident in my measured muzzle velocity of around 2700fps through a magnetospeed chrony. And even plugging in that velocity my ballistics tables don't jive with my actual dopes at various distances with the advertised g7 BC of .419. There was an event last year where a bunch of 338 shooters got together to test and compare various bullets. One of them was the Berger 300otm. They measured the g7 to .389. Plugging that BC in lines my dopes up much closer. </p><p>The fluffed/advertised BC calls for 7.3 mils to 1000. Cold bore takes me 7.5 mils to get there and plugging .389g7 gives me that solution. It actually takes me 7.6mils on a warm barrel.</p><p>Now, to better answer your question, ballistics call for 7.5 mils and 1.35seconds TOF for the 300s with a MV of 2700. The 250s at a 3050fps call for only 5.7 mils and 1.21 seconds TOF. I haven't calculated lag time and I'm sure there's more in the 250s, but the flatter trajectory is a clear advantagefor me. Since most of my shooting is 1200yds or less I think the 250s have the advantage if I can call the wind well enough.</p><p>Of course, this all assumes that I don't have a slow barrel in general and that I can get 3000fps or better.</p><p>FWIW, its a 29" bartlein barrel on a tac338 action 9.5twist 5r and its accurate. I got 1/4" groups or better at 100, a 3 shot 1.1" group at 545, and an 8" 5 shot group my first time out to 1k with it in heavy mirage and varying winds. Its the rifle in my signature.</p><p><img src="http://i813.photobucket.com/albums/zz53/bodywerks/IMG_20130816_111325_951_zps290ebdd0.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p></blockquote><p></p>
[QUOTE="Bodywerks, post: 857216, member: 62694"] I'm going off of what my ballistics tables are telling me(shooter ballistics for android). So far, while accurate, the 300s aren't performing like I hoped. I'm pretty confident in my measured muzzle velocity of around 2700fps through a magnetospeed chrony. And even plugging in that velocity my ballistics tables don't jive with my actual dopes at various distances with the advertised g7 BC of .419. There was an event last year where a bunch of 338 shooters got together to test and compare various bullets. One of them was the Berger 300otm. They measured the g7 to .389. Plugging that BC in lines my dopes up much closer. The fluffed/advertised BC calls for 7.3 mils to 1000. Cold bore takes me 7.5 mils to get there and plugging .389g7 gives me that solution. It actually takes me 7.6mils on a warm barrel. Now, to better answer your question, ballistics call for 7.5 mils and 1.35seconds TOF for the 300s with a MV of 2700. The 250s at a 3050fps call for only 5.7 mils and 1.21 seconds TOF. I haven't calculated lag time and I'm sure there's more in the 250s, but the flatter trajectory is a clear advantagefor me. Since most of my shooting is 1200yds or less I think the 250s have the advantage if I can call the wind well enough. Of course, this all assumes that I don't have a slow barrel in general and that I can get 3000fps or better. FWIW, its a 29" bartlein barrel on a tac338 action 9.5twist 5r and its accurate. I got 1/4" groups or better at 100, a 3 shot 1.1" group at 545, and an 8" 5 shot group my first time out to 1k with it in heavy mirage and varying winds. Its the rifle in my signature. [IMG]http://i813.photobucket.com/albums/zz53/bodywerks/IMG_20130816_111325_951_zps290ebdd0.jpg[/IMG] [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
powder/load recommendation 338lm/berger 250otm
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