NRA NRA Tool Usage & Shop Equipment 2 — Questions and Answers
Question 1: What is the function of a chamber reamer?
- To smooth the bore rifling
- To cut or finish the chamber to the correct dimensions in a new or rebarreled firearm (Correct answer)
- To remove burrs from the muzzle crown
- To resize the barrel bore diameter
Correct answer: To cut or finish the chamber to the correct dimensions in a new or rebarreled firearm
A chamber reamer is a precision cutting tool that cuts the chamber to SAAMI-specified dimensions, ensuring correct headspace and a properly formed chamber.
Question 2: When would a gunsmith use a pilot bushing in a drilling operation?
- To guide the drill bit accurately to prevent walking and ensure perpendicular holes (Correct answer)
- To protect the drill bit from breaking
- To measure the depth of the hole
- To size the drill bit to the correct diameter
Correct answer: To guide the drill bit accurately to prevent walking and ensure perpendicular holes
A pilot bushing is a hardened guide inserted in a drill jig to precisely locate and guide the drill bit, preventing wandering and ensuring accurate hole placement.
Question 3: What is the purpose of a stoning fixture when working on trigger components?
- To hold trigger components at a consistent angle while polishing engagement surfaces (Correct answer)
- To measure trigger engagement depth
- To drill new pins in the trigger group
- To check trigger reset distance
Correct answer: To hold trigger components at a consistent angle while polishing engagement surfaces
A stoning fixture holds trigger parts (hammer, sear) at the correct angle while an Arkansas or ceramic stone polishes engagement surfaces to improve trigger feel.
Question 4: What is a tap used for in a gunsmithing shop?
- To cut external threads on a barrel
- To cut internal threads in a hole for a screw or threaded component (Correct answer)
- To measure thread pitch
- To remove broken screws
Correct answer: To cut internal threads in a hole for a screw or threaded component
A tap is a hardened cutting tool used to cut internal threads inside a drilled hole to accept a machine screw or threaded pin.
Question 5: What is the purpose of using a padded vise jaw or aluminum jaw inserts in gunsmithing?
- To provide extra clamping force
- To prevent marring or damaging the surface finish of firearm components (Correct answer)
- To measure the clamping force applied
- To electrically isolate the part from the vise
Correct answer: To prevent marring or damaging the surface finish of firearm components
Padded or aluminum jaw inserts are softer than the steel vise jaws and protect the blued, parkerized, or polished finish of firearm components from scratches and damage.
Question 6: What type of file should a gunsmith use to remove metal from a firearm component without leaving deep scratches?
- A rasp
- A bastard-cut file
- A smooth or second-cut file (Correct answer)
- A wood file
Correct answer: A smooth or second-cut file
A smooth or second-cut file removes metal slowly with fine teeth, leaving a cleaner surface than coarser files, making it appropriate for final fitting of firearm parts.
NRA NRA Tool Usage & Shop Equipment 2
What is the function of a chamber reamer?