An improved coupler-knuckle assembly is comprised of a coupler body, a knuckle, and at least two knuckle retainer plugs. The knuckle has an internal coring geometry that increases the cross-sectional area of the throat portion of the knuckle compared to previous designs. The present invention's knuckle design includes a top and a bottom tapered holes in the knuckle with a locking groove at the bottom of each tapered hole for the knuckle retainer plugs to snap into. The knuckle retainer plugs are inserted through the coupler body and into the tapered holes in the knuckle. The improved coupler-knuckle assembly of the present invention reduces fatigue on the coupler, knuckle, and knuckle pin, prevents misalignment of the coupler-knuckle assembly, and prevents knuckle pin breakage.