Trajectory Rod
Definition
A rigid fibreglass or aluminium rod inserted through a bullet wound channel and aligned with the channel geometry to define the bullet's path as a straight line in three dimensions. The rod is extended forward and backward to project the trajectory.
- Material
- Fibreglass or aluminium (rigid construction)
- Primary use
- Demonstrating bullet path and measuring entry angles in three dimensions
- Where it goes
- Inserted through bullet holes or wound channels during scene reconstruction
Common questions
What is a trajectory rod and what is it made of?+
A trajectory rod is a rigid probe made from fibreglass or aluminium that is inserted through a bullet hole or wound channel to physically demonstrate the bullet's path. It shows the line of flight in three dimensions so investigators can understand how the shot was fired.
How is a trajectory rod used in crime scene reconstruction?+
The rod is carefully aligned with the bullet wound channel geometry to define the bullet's straight-line path. It is then extended forward and backward beyond the entry point to project where the bullet came from and where it would have gone, helping measure entry angles in both vertical and horizontal planes.
Why is a trajectory rod important for shooting scenes?+
It provides physical, visual proof of the shooter's position and aiming angle by marking the actual path the bullet took through the scene. This is much clearer than describing angles on paper and helps reconstruct exactly what happened during the incident.
Related terms
- Angle of Impact
- The angle between the bullet's trajectory and the surface it penetrates, measured from the surface plane. Calculated from entry-hole geometry: sin(angle) =...
- Ballistic Solver
- Software (JBM Ballistics, Strelok Pro, Hornady 4DOF, AB Quantum) that computes trajectory accounting for drag, BC, muzzle velocity, and atmospheric conditions. Supplementary...
- Battle-Sight Zero (BZO)
- The zero range selected by a military or paramilitary organisation as the standard setting for field use. US Army M4: 300 m....
- Bore Axis
- The centreline of the barrel through which the bullet travels. The starting reference line for measuring gravity drop and the elevation difference...
- Bullet Trajectory Kit (BTK)
- A laser-based trajectory projection system by Sirchie that replaces the physical rod with a laser module, projecting a visible beam along the...
- Bullet Wipe (Metal Wipe)
- The grey-black ring of bullet-jacket material (grease, metal oxides, carbon) deposited around the margin of an entry hole as the bullet's periphery...
- Burke and Rowe 1992
- The primary peer-reviewed study of bullet ricochet behaviour on concrete, asphalt, and vehicle metal surfaces, published in the Journal of the Forensic...
- Faro Focus 3D
- A terrestrial laser scanner used for crime-scene documentation, capturing a full-resolution point-cloud model of the scene at millimetre accuracy. Trajectory rods or...
- Gravity Drop
- The vertical distance a bullet falls below the bore axis at a given horizontal range, accumulating continuously from the instant of muzzle...
- Keyhole Wound
- An asymmetric teardrop-shaped bullet entry hole produced when the bullet strikes the surface sideways or is unstabilised, indicating close-range fire (pre-stabilisation) or...
- 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...
- Ortho-Tron Projection Rod
- A commercial trajectory rod system manufactured by Sirchie, widely used by the FBI Evidence Response Team and forensic laboratories internationally, providing standardised...
Explained in these topics
- Bullet Trajectory Analysis, Ricochet and Scene ReconstructionA rigid fibreglass or aluminium rod inserted through a bullet wound channel and aligned with the channel geometry to define the bullet's path as a straight lin...
- Parabolic Flight Path: Gravity Drop, Zero Range and Point-Blank RangeA physical probe inserted through a bullet hole in a surface to physically demonstrate the line of flight. Used in scene reconstruction to measure entry angle...