Firing Circuit Monitor

The Butler National Firing Circuit Module is a critical piece of test equipment for weapon operators, allowing them to quickly and easily verify the integrity of the weapon system before the mission has started.

Installed on the cable between the gun and the aircraft, the FCM makes the gun safe and monitors for a firing pulse. When a normal firing pulse is detected, the associated “Primer” and “Bolt” lights will both cycle, indicating that the weapon system is good. Maintenance instructions for error cases (if both lights do not cycle) are engraved on the carrying case.


  • Installs quickly to Gun Cable
  • Automatic Safe-Gun Feature – the M230 will not fire live electric-primed rounds while the FCM is installed.
  • Simulates primer load for accurate system tests
  • Powered by the system/vehicle – no batteries required
  • Self-Test Feature
  • Instructions and Diagnostic Guide are laser-engraved on the unit
  • Ruggedized Case included

Hangfire Override Modules

Butler National Hangfire Override Modules (HOMs) enable weapon system operators to dry-cycle guns for testing and maintenance.

Typically, when a motor-driven gun dry cycles or “fires” a dummy round, the lack of a recoil impulse causes the weapon system to enter an error mode. However, with the Butler National HOM attached and enabled, a simulated recoil impulse is provided – allowing the gun to continue cycling as it would had a live round been fired.

By allowing Dry Cycle Testing in addition to testing with substitute rounds, Butler National Hangfire Override Modules (HOMs) provide weapon operators with valuable diagnostic capabilities.

Gun Emulator


  • Interface to the weapon system just like the gun
  • Inject single or multiple faults to test Control Units & Vehicle Systems
  • Interfaces to Vehicle Control Systems to monitor system status

See the Gun Emulator page >

BNC: Supporting the missions that matter most.

From controlling the guns on the latest military vehicles to protecting the fuel tanks of commercial aircraft, Butler National Corporation products serve mission-critical roles in sectors where failure is not an option.

Power Distribution Panel from the BNC Portable Weapon System Integration Kit, operating a chain gun on a static mount