NRA NRA Sight Systems & Optics 2

Question 1

A rifle scope marked '3-9x40' indicates which combination of specifications?

Accepted Answer

3 to 9 power variable magnification, 40mm objective lens diameter

Answer

3 to 9 meter effective range, 40mm tube diameter

Answer

3 to 9 MOA adjustment range, 40mm eye relief distance

Answer

3 to 9 inch click value, 40mm ocular lens diameter

Question 2

What is 'eye relief' as it applies to rifle scopes?

Accepted Answer

The distance between the eyepiece and the shooter's eye that produces a full, clear field of view

Answer

The range of magnification adjustment available on a variable scope

Answer

The diameter of the ocular (eyepiece) lens in millimeters

Answer

The amount of reticle adjustment available from center

Question 3

In a first focal plane (FFP) variable scope, how does the reticle behave when magnification is changed?

Accepted Answer

The reticle grows and shrinks proportionally with changes in magnification

Answer

The reticle remains the same apparent size at all magnification settings

Answer

The reticle shifts laterally to track bullet drop compensation

Answer

The reticle illumination automatically adjusts with magnification

Question 4

What is parallax error in a rifle scope, and when does it occur?

Accepted Answer

The apparent movement of the reticle relative to the target when the shooter's eye moves off the optical axis

Answer

Chromatic lens distortion that blurs the target image at high magnification

Answer

Vertical drift of the point of impact caused by barrel heating

Answer

Mechanical backlash in the windage or elevation turrets

Question 5

What is the function of a rifle scope's windage adjustment turret?

Accepted Answer

To move the reticle or impact point horizontally left or right

Answer

To change the focal plane of the objective lens for parallax correction

Answer

To adjust the elevation of the reticle for bullet drop compensation

Answer

To control the illumination brightness of an illuminated reticle

Question 6

What does 'BDC' designate when describing rifle scope reticles?

Accepted Answer

Ballistic Drop Compensator

Answer

Base Distance Calibration

Answer

Barrel Diameter Correction

Answer

Binocular Diopter Control

Question 7

Which standardized military rail specification (MIL-STD-1913) provides uniform cross-slots for mounting scopes and accessories on firearms?

Accepted Answer

Picatinny rail

Answer

Dovetail rail

Answer

Weaver rail

Answer

Tip-off rail