A mounting apparatus for mounting accessories to firearms comprises an accessory lug, a frame, and an accessory lug fixture. The accessory lug is fixed to the firearm. The accessory lug has a lug cross-section shaped to prevent the accessory lug from being received within a standard bayonet lug fixture. The frame includes an accessory-holding portion adapted for holding the accessory and an accessory lug fixture connected to the frame. The accessory lug fixture has a lug-receiving channel with a channel cross-section. The channel cross-section is different than a cross-section of a standard bayonet lug. The channel cross-section is shaped to permit the channel to receive either the accessory lug or a standard bayonet lug in a manner for securing the frame and the accessory to the firearm. In another aspect of the present invention, an apparatus for mounting a flashlight to a firearm comprises a frame mountable to the firearm, a first flashlight-retaining member connected to the frame, and a second flashlight-retaining member connected to the frame and spaced from the first flashlight-retaining member. The second flashlight-retaining member is moveable relative to the first flashlight-retaining member between first and second positions. The second flashlight-retaining member is connected to the frame by a resilient member, which permits movement of the second flashlight-retaining member between its first and second positions. The resilient member biases the second flashlight-retaining member toward its second position. The first and second flashlight-retaining members are adapted for permitting engagement and disengagement of the flashlight with the first and second flashlight-retaining members when the second flashlight-retaining member is in its first position and for securing the flashlight relative to the frame when the second flashlight-retaining member is in its second position.