So whats the real deal with all this ES/SD BS

[Ccrider]

Node/tune that shifts "point of impact" low on target?

Or lower on something else?

Sorry, I don't understand.

The barrel whips up and then goes down and whips back up. The node was described as the time period in the harmonics where the barrel is at the top. or bottom of the whip. When at the top, the poi will be up on the target. As the barrel whips back down to the bottom the poi will be lower on the target.

The powder charge, seating depth and neck tension effect where the bullet is in the barrel vibration cycle when it leave the barrel.

 

[CharlieNC]

For differences in velocity a ballistic calculator gives the impact on vertical assuming there are no barrel harmonics, faster hits higher in a near perfect linear response. Increasing charge and velocity hits lower to form a node due to barrel harmonics. Couple the harmonic target response with a ballistic calculator and you can better predict nodes at different distances.

 

[Bart B.]

Ccrider, thanks for clarifying.

The best place for all bullets to leave is on the upswing. Slower bullets have to leave at higher angles to the LOS than faster ones to strike the same place on target.

The frequency the muzzle axis vibrates at is fixed. Where bullets leave is determined by muzzle velocity and barrel time. If bullets leave centered about the top antinode of the barrel whip, the slower half will leave on the down swing at the same angles as the faster ones. The reverse if bullets leave about the bottom antinode.

In vibrating things, a "node" refers to midpoint between extremes. "Antinodes" are the extreme points.

Have you ever seen Varmint Al Harral's or Geoffrey Kolbe's website pages on barrel whip compensation?