Devices, assemblies, systems, and methods for providing a quick and easy accessory mounting device for mounting to a multiple slot interface, such as a multiple slot rail on a firearm. The mounting device/assembly allows for firearm accessories such as foregrips, bipods, scopes lights, bayonets, and the like, can be easily interchangeably attached to the multiple slot interface on the firearm. A wedge member having two wedge legs can be activated to move below the device/assembly and attach to a pair of slots in the multiple slot rail on the firearm. A torque screw can be also used to lock the wedge legs in place.