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Old November 12, 2012, 10:04 AM   #32
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 4,731
Unclenick, I agree that the charge weight that shoots the bullet out at the optimum time produces best accuracy at some range. But that accuracy is only "best" in a portion of the range from muzzle to a far distant limit. For example, from muzzle to 600 yards, the smallest MOA value may well be at 400 yards and the MOA value at other ranges a bit bigger. A different charge weight will send the bullet out at a different place in the muzzle's vertical swing. And that'll move the most accurate range to another one and make the worse accuracy number get bigger. This is what happens with muzzle velocity spread vs muzzle exit angle compensate for bullet drop. There's one area on the muzzle axis vertical spread that's best for accuracy up to some range. The Brits knew this well with their arsenal .303 ammo shot in their SMLE's; it shot more accurate at 600 yards and beyond than the Mauser 98 action rifles did with the same ammo. But the Mausers (with the same barrel dimensions) shot more accurate at ranges shorter than 600 yards compared to the SMLE's. Each rifle had its own barrel whip issues that differed because of how recoil forces moved each barreled action around in the stocks before the bullet left the muzzle.

Regarding the "shock wave" the OCW believers have traveling in a barrel, where does it start at? I think that if it's any place other that at the case head, there'll be two of them when it starts; one going backwards toward the bolt face and the other forward towards the muzzle. That doubles the number of shock waves in a barrel.

Jimro, videos I've seen of rifle barrels whipping like a fishing rod does showed the vibrations damped out after about 6 or 7 cycles. The major ones have the most effect on muzzle axis angle have resonant and harmonic frequencies up to about 400 Hz. After a 2 to 4 millisecond barrel time (depending on centerfire rifle muzzle velocities), the bullet's left the barrel and nothing the barrel can do after that will effect its path. So there's only about one plus major whip cycle while the bullet's going through the barrel.

Last edited by Bart B.; November 12, 2012 at 06:16 PM.
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