NRA Firearm Repair & Restoration Techniques 3 — Questions and Answers
Question 1: When fitting a new extractor to a semi-automatic pistol, the gunsmith should verify correct tension by:
- Measuring extractor protrusion with a dial caliper and comparing to spec
- Pressing a loaded cartridge rim under the extractor and confirming snap-in with firm resistance (Correct answer)
- Polishing the extractor claw until the cartridge slides freely under it
- Verifying that the extractor spring coil count matches the OEM part
Correct answer: Pressing a loaded cartridge rim under the extractor and confirming snap-in with firm resistance
Proper extractor tension is confirmed when a cartridge snaps under the extractor with firm resistance and does not rattle or fall out when the pistol is tilted.
Question 2: A double-action revolver's trigger pull is excessively heavy. Which spring is most often replaced or reduced to improve DA pull weight?
- Cylinder latch spring
- Mainspring (hammer spring) (Correct answer)
- Trigger rebound spring
- Crane lock spring
Correct answer: Mainspring (hammer spring)
The mainspring (hammer spring) is the primary contributor to double-action trigger pull weight, and replacing it with a reduced-power unit is the standard approach.
Question 3: During a stock inlet repair on a wood-stocked rifle, the gunsmith finds a cracked wrist. The preferred structural repair method is to:
- Wrap the wrist with fiberglass tape and reapply finish
- Inject thin cyanoacrylate into the crack, clamp, and reinforce with a hidden steel cross-pin if needed (Correct answer)
- Fill the crack with wood filler and refinish
- Replace the stock with a synthetic unit
Correct answer: Inject thin cyanoacrylate into the crack, clamp, and reinforce with a hidden steel cross-pin if needed
Thin CA wicks into the grain, bonds the crack, and a cross-pin provides mechanical reinforcement in high-stress wrist areas.
Question 4: What does a 'go' gauge confirm when checking chamber dimensions?
- The chamber is cut to maximum allowable dimensions
- The bolt will close on a cartridge at minimum safe headspace (Correct answer)
- The chamber is too short and needs reaming
- The barrel throat is properly aligned with the chamber
Correct answer: The bolt will close on a cartridge at minimum safe headspace
A go gauge is machined to minimum headspace; if the bolt closes on it, the chamber is at least at minimum safe dimensions and will accept factory ammunition.
Question 5: A shotgun with a loose action body-to-stock joint is being repaired. After tightening the stock bolt, the correct next step is to:
- Bed the action in the stock using an epoxy bedding compound (Correct answer)
- Spray the joint with penetrating oil to prevent future loosening
- Sand the stock inlet slightly larger for a free-floating fit
- Pin the action to the stock with a roll pin through the receiver
Correct answer: Bed the action in the stock using an epoxy bedding compound
Epoxy bedding fills micro-gaps and creates a perfect, stress-free mating surface between the action and stock, eliminating the play that causes looseness.
Question 6: When polishing the feed ramp of a 1911-style pistol, the gunsmith should avoid removing material from which area?
- The lower throat of the barrel's feed ramp
- The frame ramp below the barrel hood
- The junction of the frame ramp and the barrel ramp (the ramp-to-ramp transition) (Correct answer)
- The top surface of the barrel hood
Correct answer: The junction of the frame ramp and the barrel ramp (the ramp-to-ramp transition)
Removing material at the ramp-to-ramp transition creates a gap or ledge that catches cartridge noses, causing the very feed failures the polish was meant to prevent.
Question 7: Which method is used to identify high spots when fitting a bolt's locking lugs for full-contact engagement?
- Use a feeler gauge between each lug and its seat
- Coat the lugs with machinist's blue (Dykem) and close the bolt to reveal contact marks (Correct answer)
- Measure lug width with a micrometer and compare to receiver dimensions
- Fire proof loads and inspect primer for flattening
Correct answer: Coat the lugs with machinist's blue (Dykem) and close the bolt to reveal contact marks
Machinist's blue (Dykem) transfers off the lugs onto the receiver seats where contact occurs, clearly showing which areas are bearing and which need lapping.
NRA Firearm Repair & Restoration Techniques 3
When fitting a new extractor to a semi-automatic pistol, the gunsmith should verify correct tension by: