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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
velocity vs accuracy in long range shooting
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<blockquote data-quote="Bart B" data-source="post: 679832" data-attributes="member: 5302"><p>As one of the Palma Team members who helped develop the first loads for that bullet when prototypes were given to us in early 1991, I can attest to its accuracy as I shot the high 5-day aggregate score in the first match it was used. It quickly became a favorite. 29 inch barrels are about minimum so they can be shot at least 2900 fps to remain supersonic through 1000 yards. After they were first used in a big long range match in late 1991, top long range competitors from around the world shooting them said they'd never shot bullets that accurate. A couple dozen of them told me they shot no worse than 1/2 MOA at 600 yards; not too shabby for new cases, metered powder charges with a 1/3 grain spread and bullet runout of up to 3/1000ths. Soon thereafter, that 155-gr. bullet was set as the standard for all long range matches shot under the International Palma Committee's rules. In the USA, the shooters handload those bullets. In other countries, they aren't allowed handloads and have to use arsenal ammo that's loaded with Sierra 155's in their big matches.</p><p></p><p>The half dozen of us developing and testing loads were quite pleased with our work and since then, when IMR4895 was the powder of choice, Varget is now a better choice. And now there's a newer version with higher BC that's supposed to be better. I shot one test group in 1992 at 800 yards with the resultant load; 45.3 grains of IMR4895, Sierra 155 seated to touch the lands + .010", Federal 210M primer in a Winchester unprepped case full length sized: here's the 20-shot test group with shots 1 and 2 being the first two from a cold, clean barrel:</p><p></p><p><img src="http://farm4.static.flickr.com/3614/3394146444_2d5f4c3e52_m.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>The less jump to the rifling there is, the higher the muzzle velocity is. It doesn't change very much and some folks are hard pressed to tell the difference between 50/1000ths jump and zero jump. Pressure's also higher with shorter jumps to the lands. Sometimes one has to cut their charge by a grain if the seat bullets to jam into the lands when loaded, but that's typically what produces the best accuracy.</p></blockquote><p></p>
[QUOTE="Bart B, post: 679832, member: 5302"] As one of the Palma Team members who helped develop the first loads for that bullet when prototypes were given to us in early 1991, I can attest to its accuracy as I shot the high 5-day aggregate score in the first match it was used. It quickly became a favorite. 29 inch barrels are about minimum so they can be shot at least 2900 fps to remain supersonic through 1000 yards. After they were first used in a big long range match in late 1991, top long range competitors from around the world shooting them said they'd never shot bullets that accurate. A couple dozen of them told me they shot no worse than 1/2 MOA at 600 yards; not too shabby for new cases, metered powder charges with a 1/3 grain spread and bullet runout of up to 3/1000ths. Soon thereafter, that 155-gr. bullet was set as the standard for all long range matches shot under the International Palma Committee's rules. In the USA, the shooters handload those bullets. In other countries, they aren't allowed handloads and have to use arsenal ammo that's loaded with Sierra 155's in their big matches. The half dozen of us developing and testing loads were quite pleased with our work and since then, when IMR4895 was the powder of choice, Varget is now a better choice. And now there's a newer version with higher BC that's supposed to be better. I shot one test group in 1992 at 800 yards with the resultant load; 45.3 grains of IMR4895, Sierra 155 seated to touch the lands + .010", Federal 210M primer in a Winchester unprepped case full length sized: here's the 20-shot test group with shots 1 and 2 being the first two from a cold, clean barrel: [IMG]http://farm4.static.flickr.com/3614/3394146444_2d5f4c3e52_m.jpg[/IMG] The less jump to the rifling there is, the higher the muzzle velocity is. It doesn't change very much and some folks are hard pressed to tell the difference between 50/1000ths jump and zero jump. Pressure's also higher with shorter jumps to the lands. Sometimes one has to cut their charge by a grain if the seat bullets to jam into the lands when loaded, but that's typically what produces the best accuracy. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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velocity vs accuracy in long range shooting
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