A knuckle of a coupler of a rail vehicle includes a leading beam having a pulling face, a lateral offset beam extending from the leading beam, a tail extending from the lateral offset beam, an extension wall extending from the lateral offset beam towards an end of the tail, and a tapered lock engagement wall extending from the extension wall to the end of the tail. The tapered lock engagement wall is angled in relation to the extension wall. The tapered lock engagement wall is configured to engage an interior face of a main body of a lock of the coupler. The interior face defines a knuckle-engaging surface that is configured to bear against the tapered lock engagement wall.