NRA Firearm Finishing & Surface Treatments Flashcards

What is the purpose of 'bead blasting' or 'sandblasting' a firearm's metal parts before finishing?

Answer: To create a uniform matte surface texture that improves coating adhesion and hides machining marks

Abrasive blasting produces a consistent, clean surface profile that maximizes coating adhesion and gives a uniform, non-reflective appearance.

What is 'rust bluing' and what makes it distinctive compared to hot bluing?

Answer: A slow process that deliberately induces and converts rust to a stable black oxide finish, producing exceptional depth and durability

Rust bluing repeatedly applies an oxidizing solution, allows rust to form, cards it off, and boils the part to convert the oxide — producing a deep, hard, beautiful finish.

What does 'case hardening' refer to in the context of firearm parts and finishes?

Answer: A heat treatment process that hardens the outer surface of steel parts while leaving the core tough

Case hardening (carburizing or nitriding) diffuses carbon or nitrogen into the surface layer, making it hard and wear-resistant while the core remains ductile.

When applying Cerakote, what temperature is typically required to cure the coating?

Answer: Approximately 250–300°F in a curing oven for 1–2 hours

Cerakote H-series coatings are cured in an oven at approximately 250–300°F, which polymerizes the coating for maximum hardness and adhesion.

What is 'Tennifer' (also known as Melonite or QPQ) as used on Glock slides?

Answer: A ferritic nitrocarburizing salt-bath process that diffuses nitrogen and carbon into the steel surface

Tennifer/Melonite/QPQ is a salt-bath nitrocarburizing process that creates an extremely hard, corrosion-resistant surface layer integral to the metal, not a coating on top.

Why is it important to maintain proper film thickness when applying spray-on coatings like Cerakote?

Answer: Improper thickness causes dimensional changes that can affect part fit, function, and tolerance-critical areas

Coating thickness must stay within specification (typically 0.001" for Cerakote) to avoid binding in tight-tolerance areas like bores, chambers, and locking surfaces.