The present disclosure is directed to a locking assembly to attach a quickset casing head of a wellhead assembly to a landing mandrel attached to a surface casing in a drilling operation. A locking ring, comprised of a plurality of arcuate segments, is arranged between the quickset casing head and the landing mandrel. Each of the plurality of arcuate segments is clamped down onto the landing mandrel with a plurality of radially spaced lockdown bolts fastened through the quickset casing head. The clamping enables a seal between the quickset casing head and the landing mandrel without requiring arduous welding.