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Rifles, Reloading, Optics, Equipment
Reloading
Questions on 300 RUM ladder testing
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<blockquote data-quote="Bart B" data-source="post: 778116" data-attributes="member: 5302"><p>Folks need to realize that the OCW system is based on one huge myth and one big error.</p><p></p><p>The huge myth is that when the muzzle's expanded by a pressure wave, accuracy is bad. </p><p></p><p>But all those 7.62 NATO Garands the USN and USAF used in competition with their lands and grooves worn away 3/4" behind the muzzle with no copper wash from pushing steel cleaning rods down the muzzle after 3000 rounds still shot just as accurate as when new; under 4 inches at 600 yard with good lots of commercial Federal match ammo. And countless match grade bolt guns with a front sight band clamped on their muzzle had smaller bore and groove diameters under that band than behind it; those barrels shot just as accurate with or without that band.</p><p></p><p>The big error's in that pressure wave's speed and starting point in the barrel. </p><p></p><p>Depending on whose data one reads, sound travels in stainless steel between 13,000 and 18,000 fps. Mechanical engineers doing vibration analysis typically use about 16,000 fps. But where does that pressure wave start at? And there'll be several breech to muzzle cycles of that pressure wave in the 1.X milliseconds the bullet's in the barrel. If the wave starts anywhere other than the bolt face, there'll be two of them for each shot; one starting forward and another starting backwards. Now there's two shock waves moving back and forth in the barrel. each making several round trips until the bullet exits. It's the same as a rock thrown in the lake; waves go in all directions form its entry point.</p><p></p><p>And what about the same load shooting the same excellent accuracy level at long range from several different barrel lengths leaving at different velocities? The timing of bullet exit to shock wave position's all over the scale.</p><p></p><p>To say nothing about the accuracy level of all loads tested will have to be extremely good to discriminate what caused the difference in bullet drop's cause between muzzle velocity and other three or four things that causes vertical shot stringing.</p><p></p><p>One's better off shooting at least 10 shots with each load then using the one that shot the smallest group.</p></blockquote><p></p>
[QUOTE="Bart B, post: 778116, member: 5302"] Folks need to realize that the OCW system is based on one huge myth and one big error. The huge myth is that when the muzzle's expanded by a pressure wave, accuracy is bad. But all those 7.62 NATO Garands the USN and USAF used in competition with their lands and grooves worn away 3/4" behind the muzzle with no copper wash from pushing steel cleaning rods down the muzzle after 3000 rounds still shot just as accurate as when new; under 4 inches at 600 yard with good lots of commercial Federal match ammo. And countless match grade bolt guns with a front sight band clamped on their muzzle had smaller bore and groove diameters under that band than behind it; those barrels shot just as accurate with or without that band. The big error's in that pressure wave's speed and starting point in the barrel. Depending on whose data one reads, sound travels in stainless steel between 13,000 and 18,000 fps. Mechanical engineers doing vibration analysis typically use about 16,000 fps. But where does that pressure wave start at? And there'll be several breech to muzzle cycles of that pressure wave in the 1.X milliseconds the bullet's in the barrel. If the wave starts anywhere other than the bolt face, there'll be two of them for each shot; one starting forward and another starting backwards. Now there's two shock waves moving back and forth in the barrel. each making several round trips until the bullet exits. It's the same as a rock thrown in the lake; waves go in all directions form its entry point. And what about the same load shooting the same excellent accuracy level at long range from several different barrel lengths leaving at different velocities? The timing of bullet exit to shock wave position's all over the scale. To say nothing about the accuracy level of all loads tested will have to be extremely good to discriminate what caused the difference in bullet drop's cause between muzzle velocity and other three or four things that causes vertical shot stringing. One's better off shooting at least 10 shots with each load then using the one that shot the smallest group. [/QUOTE]
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Questions on 300 RUM ladder testing
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