All Murray worm drive clamps are manufactured with a small amount of lubricant on the screw.
For plated carbon steel screws the zinc plating serves as the lubricant… whereas all of the stainless screws utilize a supplemental (clear) wax compound.
Regarding stainless screws… over time the wax compound may dry up or be driven off by in-service temperatures… or harsh environments. This may leave the clamp assembly in a totally dry or under-lubricated state. If this clamp were to be re-used as-is it might be found to be under-performing with regard to expected torque-tension characteristics.
Most clamps can be restored to acceptable performance levels in the field by applying a small amount of lubricant… motorcycle chain wax… WD-40… or similar products have given good performance.Download Tech Tip