A chopper knife assembly for use by an agricultural harvester. The chopper knife assembly includes a mounting lug with a fulcrum, wedge, and counterwedge; and at least one bladed knife attached to the mounting lug between the wedge and counterwedge; the assembly is held in place by an attachment means. The bladed knives are able to pivot on the fulcrum of the mounting lug during use, thereby forcing the knife blades onto the counterwedges to provide a more secure retention means.