The lower parts kit for an AR-15 usually contains all of the pins/detents and springs necessary to complete the lower receiver.

Some lower parts kits will omit the fire control, safety, and pistol grip – or may exchange/upgrade these items for better-than-mil-spec quality parts.

Traditionally, a complete lower parts kit contains:

    • Bolt Catch,
    • Bolt Catch Plunger,
    • Bolt Catch Roll Pin,
    • Bolt Catch Spring,
    • Buffer Retainer,
    • Lower-Parts-Kit

    • Buffer Retainer Spring,
    • Disconnect,
    • Disconnect Spring,
    • Hammer,
    • Hammer Pin,
    • Hammer Spring,
    • Magazine Catch,
    • Magazine Catch Button,
    • Magazine Catch Spring,
    • Pistol Grip (A2 style),
    • Pistol Grip Lock Washer,
    • Pistol Grip Screw,
    • Pivot Pin,
    • Pivot Pin Detent,
    • Pivot Pin Detent Spring,
    • Selector,
    • Selector Detent,
    • Selector Detent Spring,
    • Takedown Pin,
    • Takedown Pin Detent,
    • Takedown Pin Detent Spring,
    • Trigger,
    • Trigger Guard,
    • Trigger Guard Roll Pin,
    • Trigger Pin,
    • Trigger Spring