Battle-Sight Zero (BZO)
Definition
The zero range selected by a military or paramilitary organisation as the standard setting for field use. US Army M4: 300 m. Indian Army INSAS: 200 m. UK SA80 A3: 300 m.
- Definition
- Standard field zero range set by an organisation
- US Army M4
- 300 m
- Indian Army INSAS
- 200 m
- UK SA80 A3
- 300 m
Common questions
Why does BZO matter to a ballistic trajectory reconstruction?+
The zero range fixes the sight picture assumption a shooter was likely using, so knowing the standard-issue BZO for a given weapon and force helps a reconstruction estimate the expected point of aim versus point of impact at a given distance, which feeds into trajectory and shooter-position analysis.
Does BZO stay fixed for a weapon regardless of unit or mission?+
No. It is a chosen doctrinal setting, and different services or even different units within the same service can select a different BZO for the same weapon platform depending on expected engagement distances, so it must be confirmed for the specific unit involved rather than assumed from the weapon type alone.
Related terms
- Ballistic Solver
- Software (JBM Ballistics, Strelok Pro, Hornady 4DOF, AB Quantum) that computes trajectory accounting for drag, BC, muzzle velocity, and atmospheric conditions. Supplementary...
- Bore Axis
- The centreline of the barrel through which the bullet travels. The starting reference line for measuring gravity drop and the elevation difference...
- Gravity Drop
- The vertical distance a bullet falls below the bore axis at a given horizontal range, accumulating continuously from the instant of muzzle...
- Near-Zero Crossing
- The shorter of the two distances at which the bullet's trajectory intersects the line of sight. For a rifle zeroed at 300...
- Point-Blank Range (PBR)
- The maximum distance at which the bullet stays within the vital-zone radius above or below the line of aim without the shooter...
- Trajectory Rod
- A rigid fibreglass or aluminium rod inserted through a bullet wound channel and aligned with the channel geometry to define the bullet's...
- Vital Zone
- The defined target area used to compute point-blank range. For human thorax: typically 20 cm diameter (10 cm radius) centred on the...
- Zero Range
- The horizontal distance at which the bullet's trajectory crosses the line of sight. At this range, the point of aim and point...