Frequently Used Terms in ELR/HTI
Danger Space: Is horizontal measurement expressed in yards or meters. As the bullet goes past the maximum ordinate and travels downward toward impact with the ground (ignoring the target), the danger space measurement begins at the point where the bullet is equal to the top (height) of the target and continues to when the bullet impacts the ground, again ignoring the target.
Maximum Ordinate: Is the highest point the bullet reaches along its trajectory. This is measured from the line of sight as you look through the sights to the target, not from the ground or from the line of bore. This occurs at different ranges with dirrefernt cartridges and weapons. Maximum Ordinate will never occur before the Mid-Range Trajectory. Also maximum ordinate will occur farther then mid-range trajectory as the range increases.
Mid-Range Trajectory: This is the height the bullet reaches at the true mid-range to target.
Swept Space: Is horizontal measurement that changes with the lay of the ground. Swept space is the linear measurement of the cone of fire created by shots placed at the top of the target and those placed at the bottom of target. On ground that is rising in front of the shooter, the swept space dimension will decrease; on ground that is falling away from the shooter , the swept space dimension increases.
Line of Bore: Is imaginary line measured in degrees and minutes of angle that the barrel is elevated to send the bullet traveling to the target.
Line of Sight: Is the sight line of the shooter through the optical or iron sight system to the point of aim. Often confused with Line of Bore.
Muzzle Brake Induced Error: This effect occurs when one is shooting a large bore (50BMG) rifle that is equipped with a venting-type muzzle brake. A shooter that is muscling his gun onto the desired point impact on target will experience this effect. As the bullet begins to travel down the bore, the cold air (precursor) in from of the bullet enters the muzzle brake and the brake starts to pull the rifle from the shooter's shoulder. This causes the gun to be further pulled in the direction the shooter is muscling the rifle. The MBIE effect is one of the biggest causes of misses on target of errant fliers in a group of shots. SIDENOTE: This is one of reasons why the NSWC teaches to pull the Tac50 into the shooter and basically “unload” the bipod.
ASL: Above Sea Level, referring to altitude above sea level. 2500' ASL
PRODAS: Production Design/Analysis System. A program by general electric for designing and analyzing the design of projectiles.
Danger Space: Is horizontal measurement expressed in yards or meters. As the bullet goes past the maximum ordinate and travels downward toward impact with the ground (ignoring the target), the danger space measurement begins at the point where the bullet is equal to the top (height) of the target and continues to when the bullet impacts the ground, again ignoring the target.
Maximum Ordinate: Is the highest point the bullet reaches along its trajectory. This is measured from the line of sight as you look through the sights to the target, not from the ground or from the line of bore. This occurs at different ranges with dirrefernt cartridges and weapons. Maximum Ordinate will never occur before the Mid-Range Trajectory. Also maximum ordinate will occur farther then mid-range trajectory as the range increases.
Mid-Range Trajectory: This is the height the bullet reaches at the true mid-range to target.
Swept Space: Is horizontal measurement that changes with the lay of the ground. Swept space is the linear measurement of the cone of fire created by shots placed at the top of the target and those placed at the bottom of target. On ground that is rising in front of the shooter, the swept space dimension will decrease; on ground that is falling away from the shooter , the swept space dimension increases.
Line of Bore: Is imaginary line measured in degrees and minutes of angle that the barrel is elevated to send the bullet traveling to the target.
Line of Sight: Is the sight line of the shooter through the optical or iron sight system to the point of aim. Often confused with Line of Bore.
Muzzle Brake Induced Error: This effect occurs when one is shooting a large bore (50BMG) rifle that is equipped with a venting-type muzzle brake. A shooter that is muscling his gun onto the desired point impact on target will experience this effect. As the bullet begins to travel down the bore, the cold air (precursor) in from of the bullet enters the muzzle brake and the brake starts to pull the rifle from the shooter's shoulder. This causes the gun to be further pulled in the direction the shooter is muscling the rifle. The MBIE effect is one of the biggest causes of misses on target of errant fliers in a group of shots. SIDENOTE: This is one of reasons why the NSWC teaches to pull the Tac50 into the shooter and basically “unload” the bipod.
ASL: Above Sea Level, referring to altitude above sea level. 2500' ASL
PRODAS: Production Design/Analysis System. A program by general electric for designing and analyzing the design of projectiles.
