Vertical Stringing
A group spread that runs up and down on the target, most often pointing to velocity variation or an inconsistent shooting position.
Vertical stringing describes a group whose shots stack along a tall column rather than clustering in a round knot. The shape itself is a clue. Because elevation on target is so closely tied to muzzle velocity, the most common culprit is round-to-round speed variation: a high extreme spread or a loose standard deviation across the charges will print fast rounds high and slow rounds low, and the effect magnifies with distance. Inconsistent powder charges, uneven neck tension, and temperature-sensitive powder all feed this pattern.
Position and technique add their own vertical error, since uneven recoil control, an inconsistent cheek weld, or breathing through the shot can lift or drop the muzzle. When you read a tall group, the diagnosis usually starts at the chronograph before the shooter blames the wind. So check the speed numbers first. Distinguishing velocity-driven dispersion from position-driven error is the first step toward tightening the load or the fundamentals.