Various detachable firearm mounting bracket device embodiments are provided. According to an embodiment, a detachable mounting bracket is adapted to allow users of various weapons platforms and support devices to rapidly and securely attach support devices, e.g., bipods and tripods, to a firearm in tandem. A detachable mounting bracket can comprise a housing to attach to a firearm forend, a clamping mechanism to secure the housing to a firearm, and a rail interface adapted to receive a plurality of adapters. The detachable mounting bracket device can be attached to a firearm with a clamp, screw closure, and a vertical interlock clamp. After the detachable mounting bracket is attached to a firearm, a user can easily and rapidly secure a support device to the rail interface using a plurality of adapters. Other aspects, features, and embodiments are also claimed and described.