The AR15 lower receiver vise block facilitates the mounting of a Mil-Spec AR15 receiver onto the vise block, enabling the secure fixation of the AR lower receiver to a workbench vise during maintenance and assembly tasks. Furthermore, this vise block includes a detachable buffer tube mount ring, which proves invaluable when installing a carbine buffer tube In an accurate and aligned manner onto the receiver. This mount ring securely holds and locks the carbine buffer tube In position, ensuring that the castle nut can be correctly tightened without causing any misalignment of the buffer tube. This feature guarantees precise assembly and optimal functionality.