Firearms Glossary
Comprehensive dictionary of firearms terminology with 16 terms.
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A
Absolute Co-Witness
Iron sights align in the center of the optic's window.
B
BDC Bullet Drop Compensator
A reticle with markings for holdover at various distances.
C
Co-Witness
Alignment of iron sights with an optic, allowing use of either sighting system.
E
Eye Box
The three-dimensional space behind the scope where the shooter can see the full field of view.
Eye Relief
The distance from the eyepiece to your eye where the full image is visible. Critical for safety with recoiling firearms.
F
FFP First Focal Plane
Reticle placement where the reticle size changes with magnification. Holdovers accurate at all magnifications.
H
Holographic Sight
Uses laser-generated hologram to create a reticle image. Functions even if lens is damaged.
L
Lower 1/3 Co-Witness
Iron sights visible in the lower third of the optic's window.
LPVO Low Power Variable Optic
Variable magnification scope starting at 1x, combining red dot speed with scope precision.
M
MIL Milliradian
Angular measurement equal to 3.6 inches at 100 yards. Common in tactical scopes.
MOA Minute of Angle
Angular measurement equal to 1.047 inches at 100 yards. Used for scope adjustments and accuracy measurement.
MRAD Milliradian
Same as MIL - angular measurement used in precision shooting.
P
Parallax
The apparent movement of the reticle relative to the target when the shooter's eye moves. Adjustable on precision scopes.
R
Red Dot
Non-magnifying optic that projects an illuminated dot onto the lens for fast target acquisition.
S
SFP Second Focal Plane
Reticle placement where the reticle stays the same size. Holdovers only accurate at one magnification.
Z
Zero
The point of aim equals the point of impact at a specific distance.