You won’t find anyone publishing their factory tolerances for runout.
Runout definitely has consequences for accuracy.
Assuming you have a perfect projectile and perfect bore, AND a perfect loading process such that the projectile is loaded perfectly concentric with the bore, then accuracy would be at its peak.
None of that is reality. Each complication compounds with the others. Bores are not straight nor are they constant in diameter. This lets projectiles tilt in the bore as they move. Loading pellets also deforms them to be off center in the bore. Those two plus projectile runout exaggerates the rotation of the project down the bore and along its point of aim. Thus increasing dispersion.
Increasing velocity also exacerbates those as bullet RPM increases, its rotation about its off center “axis” will cause it to spiral around its point of aim.
Chokes help as much as they hurt. They squeeze the project down around its current attitude in the bore, but if that attitude is not concentric, then it’s not really helping at best and hurting at worst.
The Hornady Podcast has some amazing episodes about internal ballistics with Jeff Seiwert, he’s a leading industry guy with decades of experience developing and consulting on the accuracy of small cal up to large cal (155mm+) systems.
Runout definitely has consequences for accuracy.
Assuming you have a perfect projectile and perfect bore, AND a perfect loading process such that the projectile is loaded perfectly concentric with the bore, then accuracy would be at its peak.
None of that is reality. Each complication compounds with the others. Bores are not straight nor are they constant in diameter. This lets projectiles tilt in the bore as they move. Loading pellets also deforms them to be off center in the bore. Those two plus projectile runout exaggerates the rotation of the project down the bore and along its point of aim. Thus increasing dispersion.
Increasing velocity also exacerbates those as bullet RPM increases, its rotation about its off center “axis” will cause it to spiral around its point of aim.
Chokes help as much as they hurt. They squeeze the project down around its current attitude in the bore, but if that attitude is not concentric, then it’s not really helping at best and hurting at worst.
The Hornady Podcast has some amazing episodes about internal ballistics with Jeff Seiwert, he’s a leading industry guy with decades of experience developing and consulting on the accuracy of small cal up to large cal (155mm+) systems.
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