The application discloses an optic mount assembly for coupling an optic mount to a side rail of a firearm. The optic mount assembly includes a clamping bar including a body and protrusions extending from opposing side surfaces of the body. The optic mount assembly includes a lever pivotally coupled to the clamping bar. The optic mount assembly includes a fastener coupling the lever to the clamping bar. The clamping bar is configured to be at least partially inserted into and engaged with a cutout of the side rail, and configured to be inserted into a cutout in an optic mount.