Description Dummy Mk18 Time Fuze. Functional Mk18 time fuzes are used in US naval high capacity and illuminating projectiles of caliber 4"/50, 5"/25, 5"/38, 5"/51, 6"/47, 6"/53, and 8"/55. Cast brass. Both base and rotating time setting frustum have lugs that could engage setting tools or mechanisms. The base also has two flats for use with a wrench in securing the fuze to a projectile body. The base is threaded for attachment to a projectile body. Rotating time setting frustum is stamped with time settings, but is staked so that it cannot rotate. The rotating time setting frustum has four slotted set screws that would have secured it to the internal mechanism. Time setting frustum is marked with: DUMMY P.S. 44 Base is marked with: MECH TIME FUZE - MK18 MOD 2 E.M. L.G.A. LOT - 364