An improved firearm bolt catch assembly for the lower receiver of a firearm, the assembly having a lift arm that retains the bolt of the firearm in a retracted position after the cartridge magazine has been emptied, such that the firearm does not need to be re-racked when an empty magazine is removed and replaced with a full magazine. The lift arm is substantially C-shaped, having an elongated middle segment and a pair of transverse legs. Each of the transverse legs is pivotally mounted onto the lower receiver. The lift arm is raised by the magazine follower when the last cartridge has been discharged. An insert assembly is also disclosed.