Function litz_drift_inches 

pub fn litz_drift_inches(sg: f64, t_s: f64) -> f64

Empirical Litz spin-drift MAGNITUDE in inches from the muzzle gyroscopic stability sg and time of flight t_s (seconds): drift_inches = 1.25 * (Sg + 1.2) * t^1.83

This is the single source of the Litz drift coefficient (MBA-1134). It is UNSIGNED — the caller applies the twist-direction sign (see litz_drift_meters). cli_api::apply_spin_drift and the fast / Monte-Carlo path both go through this so the three solver families stay bit-identical on the drift math.