Abstract: An interlock mechanism for a firearm that includes a stop lever and a cam lever is disclosed. The stop lever is coupled to a firearm safety mechanism such that when the safety mechanism is in a “fire” position the stop lever prevents the upper receiver of the rifle from being separated from the lower receiver of the rifle and when the safety mechanism is in a “safe” position the stop lever allows the upper receiver to be separated from the lower receiver. The cam lever has a “locked position” in which the upper receiver cannot be separated from the lower receiver and an “unlocked position” in which the upper receiver can be separated from the lower receiver. When the safety mechanism is in the “fire” position the stop lever prevents the cam lever from transitioning from the “locked position” to the “unlocked position”.