Thread: Accuracy at 100 vs 600 (example). Variations in accuracy at different ranges

Originally Posted by Moa Hunter

My copy of 'The Sharp Shooter' explains it as all the bullets in a group actually spiralling in the same direction as the twist of the bore (x spiral) then due air pressure building on the tip of the bullets, because they are not flying completely in line with the direction of travel. This air rolling off on the opposite side to the x spiral initiating a y spiral.

So what this means is that bullets move away from the line of sight then move back and cross it and then disperse outwards again then straighten out of these spirals again but not before they have taken their dispersive effect.
To Quote Matt and Bruce Grant: 'The occasional extraordinarily good group which shooters preserve and show off is due to y error for the shots all combining within the circle of x error at the target. Ironically, a group from the same shots taken at almost any other range would show a wider dispersion'.
What I take this to mean is that a target shooter would need to have a box of ammo tuned for each range that they will shoot at.

A link to the original work of DR FW Mann https://duienforcers.wildapricot.org...unnCo_1909.pdf

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To clarify, as explained by Grant, bullets enter the rifling non-concentric with the bore and rifling (concentricity is only an approximation, 100% concentricity is a mathematical concept, not practically achievable).
This leads to bullet WOBBLE as they are spun by the rifling, which in turn leads to a CORKSCREW, flight path.
Eventually centrifugal and aerodynamic forces cause the bullet to stop wobbling, and it flies straight from there on.... but from a random point in the spiral. Grant stated that rifle shooting targets, if enough shots are fired, show up a donut pattern of impacts for this reason.

So from this, yes, bullets fly straighter paths after the first 100 - 140 yards, but they are thrown off aim before that. The initial wobbly/corkscrew flight must have quite an energy cost too.