Andrew's table shows what the bullet paths are for each muzzle velocity when zeroed at 200 yards. At about 60% down range, the difference is the greatest at about .2". The sights are set lower for the faster load compared to the slower one; muzzle axis is a tiny bit higher for the 2650 fps one compared to the 2750 fps one..
Here's the bullet drop differences for every 25 yards of range with the same 200 yard zero using Sierra Infinity 7 software and their 30 caliber 165-gr. SBT bullet leaving at 2650 and 2750 fps:
25- .01"
50- .05"
75- .10"
100- .19"
125- .30"
150- .44"
175- .61"
200- .81"
If the barrel's stiffness lets it whip enough when fired to positively compensate for bullet velocities (bullets leave on the muzzle axis upswing; slower ones later at a higher angle than faster ones leaving sooner), that chart may well be their actual path. That depends on the barrel's stiffness as well as the center of mass/gravity of what holds the barreled action, both behind and off the bore center axis, that causes the barrel to whip from recoil forces bending it.
If the center of mass/gravity holding the barreled action is directly in line with the bore axis, the barrel won't whip at all but remain straight during barrel time as well as long after the bullet's gone regardless of how stiff or whipy it otherwise is. As most center of mass/gravity location is below the bore axis, the barrel whips in the vertical axis and in less than 1.5 major axis cycles before the bullet leaves after a 1.0 to 1.3 millisecond (typical) barrel time. Somewhere on the upswing in the middle half of its first cycle is ideal.
Here's two articles; first to explain positive compensation and second to calculate how it's done with a .308 Win chambered barrel of different profiles and weights versus center of mass/gravity of what holds it:
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/tuning_a_barrel.htm
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/barrel_vibrations.htm
Here's the bullet drop differences for every 25 yards of range with the same 200 yard zero using Sierra Infinity 7 software and their 30 caliber 165-gr. SBT bullet leaving at 2650 and 2750 fps:
25- .01"
50- .05"
75- .10"
100- .19"
125- .30"
150- .44"
175- .61"
200- .81"
If the barrel's stiffness lets it whip enough when fired to positively compensate for bullet velocities (bullets leave on the muzzle axis upswing; slower ones later at a higher angle than faster ones leaving sooner), that chart may well be their actual path. That depends on the barrel's stiffness as well as the center of mass/gravity of what holds the barreled action, both behind and off the bore center axis, that causes the barrel to whip from recoil forces bending it.
If the center of mass/gravity holding the barreled action is directly in line with the bore axis, the barrel won't whip at all but remain straight during barrel time as well as long after the bullet's gone regardless of how stiff or whipy it otherwise is. As most center of mass/gravity location is below the bore axis, the barrel whips in the vertical axis and in less than 1.5 major axis cycles before the bullet leaves after a 1.0 to 1.3 millisecond (typical) barrel time. Somewhere on the upswing in the middle half of its first cycle is ideal.
Here's two articles; first to explain positive compensation and second to calculate how it's done with a .308 Win chambered barrel of different profiles and weights versus center of mass/gravity of what holds it:
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/tuning_a_barrel.htm
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/barrel_vibrations.htm
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