NRA Firearm Customization & Modifications 3 — Questions and Answers
Question 1: When glass bedding a rifle action, what is the purpose of applying a release agent to the action before embedding it in epoxy?
- To improve adhesion between the action and epoxy
- To prevent the action from permanently bonding to the stock (Correct answer)
- To fill pits and scratches on the action
- To lubricate the action screws
Correct answer: To prevent the action from permanently bonding to the stock
A release agent prevents the bedding compound from adhering to the metal action, allowing the action to be removed cleanly once the epoxy cures.
Question 2: A customer requests a slicked-up action on their Model 70 Winchester. Which internal parts should a gunsmith polish to reduce felt friction?
- The barrel exterior and magazine follower
- The bolt body, cocking piece, and bearing surfaces inside the receiver (Correct answer)
- The trigger guard and floor plate
- The extractor and ejector pins only
Correct answer: The bolt body, cocking piece, and bearing surfaces inside the receiver
Polishing the bolt body, cocking piece ramp, and receiver bearing surfaces reduces friction during the bolt lift and cycling stroke, producing a smoother action feel.
Question 3: Which type of sighting system requires the most precise and permanent installation due to its zero-sum adjustment method?
- Ghost ring rear sight
- Fixed iron sight (dovetail style) (Correct answer)
- Red dot optic on a Picatinny rail
- Peep sight with click adjustments
Correct answer: Fixed iron sight (dovetail style)
Fixed dovetail sights have no elevation or windage adjustment screws — they must be precisely drifted or cut to the correct position during installation to achieve proper zero.
Question 4: When stippling a polymer pistol frame for improved grip, what is the most important precaution to prevent damage?
- Cooling the polymer with water during stippling
- Using low heat and testing on a scrap piece to prevent melting through the frame wall (Correct answer)
- Applying oil to the polymer before stippling
- Using only metal stippling tools
Correct answer: Using low heat and testing on a scrap piece to prevent melting through the frame wall
Polymer frames can melt through quickly with excessive heat; testing on scrap material and using controlled, low-temperature passes prevents damaging the frame structurally.
Question 5: A bolt-action rifle is shooting vertical stringing. The bedding is solid and the barrel is free-floated. What is the most likely cause?
- Stock warping from moisture
- Ammunition inconsistency in bullet seating depth or powder charge (Correct answer)
- A loose scope mount
- Front sight misalignment
Correct answer: Ammunition inconsistency in bullet seating depth or powder charge
Vertical stringing with a properly bedded, free-floated rifle most commonly points to ammunition inconsistency, particularly variations in bullet seating depth or powder charge weight.
Question 6: What is the correct procedure for setting headspace on a custom bolt-action build after fitting a new barrel?
- Use the same headspace gauge from the old barrel
- Use Go and No-Go gauges specific to the cartridge to verify minimum and maximum allowable headspace (Correct answer)
- Measure headspace with a caliper at the chamber mouth
- Fire-form a case and measure the case head expansion
Correct answer: Use Go and No-Go gauges specific to the cartridge to verify minimum and maximum allowable headspace
Go and No-Go headspace gauges verify that the chamber meets SAAMI minimum (bolt must close on Go) and does not exceed maximum (bolt must not close on No-Go), ensuring safe headspace.
Question 7: When installing a Picatinny rail scope mount on a receiver with pre-drilled and tapped holes, what is the recommended procedure for scope mount screw torque?
- Tighten screws as tight as possible by hand
- Apply thread locker and torque to manufacturer specifications, typically 15–25 in-lbs for base screws (Correct answer)
- Apply anti-seize compound and tighten until snug
- Use red thread locker and torque to 65 in-lbs
Correct answer: Apply thread locker and torque to manufacturer specifications, typically 15–25 in-lbs for base screws
Applying blue thread locker and torquing base screws to the manufacturer's specified value (usually 15–25 in-lbs) ensures secure retention without stripping the receiver threads.
NRA Firearm Customization & Modifications 3
When glass bedding a rifle action, what is the purpose of applying a release agent to the action before embedding it in epoxy?