In all Redding dies the lock ring has a piece of Bismuth captured behind the set screw which engages the die threads as the set screw is turned in. This is more costly but far more effective than a simple brass screw, which can be easily stripped and therefore made unusable.

Redding uses steel on steel for strength but places a piece of lead between the set screw and the die threads as a buffer to protect the threads from damage and provide a secure lock-up.