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Project Gunner

Sight Adjustment, Subtension & Offset Calculator

Three pieces of pure geometry that decide whether a zero session takes five rounds or fifty: how many clicks a given miss is worth on your turret, how much target your dot is actually covering, and how far below the dot the projectile still is on a close shot. No load data needed — angle holds for every cartridge.

Turret correction

Click value

The distance the group was actually shot at.

One axis at a time — do the vertical, then the horizontal.

Reticle & dot subtension

Uses the distance you entered above.

Unit

The dot covers

2.09 in

5.3 cm

The same dot in the other unit: 0.58 MRAD. If the dot covers more than the scoring area you are aiming at, the dot — not the load and not the barrel — is what is limiting your group.

Mechanical offset at close range

Bore centreline to optic centreline. A 1.93 in mount on a flat-top sits near 2.6 in.

Where the sight line and the trajectory are set to meet.

The close shot you are actually taking.

Hold this much high

2.08 in

Inside the zero the projectile has not yet climbed to the sight line, so it prints low by this much. Aim high by the same figure to put the hit where the dot is.

Declared reference conditions. One MOA is taken as the true minute, 1.047 in per 100 yd, not the rounded “inch per hundred”; one milliradian is exactly 3.6 in per 100 yd, and 1 MRAD = 3.437747 MOA. Turret and subtension figures are pure geometry and hold for any load. The mechanical offset block is straight-line geometry with drop deliberately excluded: it is valid well inside the zero distance, where drop is small against the sight height, and it is not a substitute for a trajectory table past that point.