Trigger guard assemblies for firearms include a trigger guard movable between a closed positon; and an open position providing greater access to a trigger bow of the firearm. The trigger guard assemblies also include a post that engages the trigger guard, and is movable in relation to the trigger guard between a retracted position and an extended position. When in the retracted position, the post does not interfere with movement of the trigger guard between the open and closed positions. When in the extended position, the post interferes with movement of the trigger guard between the open and closed positions, and exerts a lateral force on the firearm to further secure the trigger guard to the firearm.