NRA Metalworking & Woodworking for Gunsmithing 3

Question 1

Which type of steel is most commonly used for rifle barrels due to its combination of strength and machinability?

Accepted Answer

4140 chromoly steel

Answer

4140 chromoly steel offers an excellent balance of tensile strength, toughness, and machinability that makes it the industry standard for rifle barrels.

Question 2

When fitting a new wood stock blank to a metal action, what is the correct sequence of inletting?

Accepted Answer

Inlet the action first, then work outward to the barrel channel

Answer

Starting with the action inletting establishes the critical fit at the receiver, then extending the barrel channel ensures proper alignment throughout.

Question 3

A gunsmith is using a mill to cut a dovetail slot for a front sight. What cutter geometry is required?

Accepted Answer

Dovetail cutter with angled sides

Answer

A dovetail cutter has angled cutting faces that produce the characteristic trapezoidal profile needed to capture a dovetail-base sight.

Question 4

What does the Rockwell hardness scale 'C' (HRC) primarily measure in gunsmithing contexts?

Accepted Answer

Surface hardness after heat treatment

Answer

The Rockwell C scale uses a diamond cone indenter under load to measure surface hardness, commonly used to verify heat treatment results on hardened firearm parts.

Question 5

When checkering a pistol grip using a 60-line-per-inch pattern, what is the primary purpose of the master lines cut first?

Accepted Answer

To establish the pattern layout and spacing guides for subsequent cuts

Answer

Master lines establish the grid spacing and direction so all subsequent cuts remain parallel and evenly spaced throughout the checkering field.

(NRA) National Rifle Association Certified Gunsmith Practice Test

(NRA) National Rifle Association Certified Gunsmith Practice Test

NRA Metalworking & Woodworking for Gunsmithing 3