NRA Metalworking & Woodworking for Gunsmithing 4

Question 1

When turning a barrel tenon on a lathe, what is the critical measurement that must be achieved for proper headspace?

Accepted Answer

Length and diameter of the tenon that controls chamber-to-bolt-face distance

Answer

The tenon length and shoulder position directly control headspace by determining how far the barrel seats into the receiver relative to the bolt face.

Question 2

Which solvent is most appropriate for degreasing metal parts before bluing or Parkerizing?

Accepted Answer

Acetone, naphtha, or commercial degreaser leaving no residue

Answer

Complete degreasing using residue-free solvents is essential because any oil or grease contamination will cause bluing or Parkerizing to fail or spot.

Question 3

A walnut rifle stock develops a crack along the wrist during recoil. What is the most structurally sound repair method?

Accepted Answer

Inject thin cyanoacrylate into the crack, clamp, and reinforce with a metal wrist bolt if needed

Answer

Thin CA glue penetrates the crack by capillary action, bonds the fibers, and a cross-bolt provides additional mechanical reinforcement at the wrist's high-stress point.

Question 4

When using a surface grinder to true a receiver face, what grinding wheel specification is appropriate for hardened steel?

Accepted Answer

Fine aluminum oxide wheel rated for hardened steel

Answer

Fine-grit aluminum oxide wheels are standard for precision surface grinding of hardened steel receiver faces, providing controlled material removal without burning.

Question 5

What is the purpose of annealing the case neck area of a cartridge case, and how does it relate to gunsmithing?

Accepted Answer

It softens work-hardened brass to restore ductility and prevent cracking

Answer

Repeated firing work-hardens brass necks; annealing restores their ductility to allow proper bullet seating and prevent neck splits, knowledge useful when advising reloading customers.

(NRA) National Rifle Association Certified Gunsmith Practice Test

(NRA) National Rifle Association Certified Gunsmith Practice Test

NRA Metalworking & Woodworking for Gunsmithing 4