Combined with a patent pending fire control system, the proprietary lightweight polymer construction of the SFI-15 lower receiver provides a superior strength-to-weight ratio.
The SFI-15 uses the following metal parts:
- Takedown pin detents and springs
- Hammer/Trigger pins and springs
- Bolt catch, spring, & roll pin
- Magazine catch spring
- Pistol grip screw
- Buffer, buffer spring
- Buffer detent and spring
- Castle nut
- Receiver end plate
All other parts are constructed using polymer
