M600 chemical fuze was removed from service around 1953 and replaced by the M603 single-impulse fuze, which used a mechanical trigger mechanism i.e. a belleville spring. The M603 fuze is inherently safe to handle and much more reliable. In addition to the standard M603 fuze, two additional fuzes are available: the M624 tilt-rod fuze (which offers full-width attack capability) and the M608 double-impulse fuze. The M624 fuze requires 3.75 pounds of pressure to move the tilt rod, and once it exceeds 20 degrees of tilt the mine will detonate. The M608 double-impulse fuze will not detonate the mine when the first tank drives over it: instead, it simply arms itself so that the mine detonates when the second vehicle (e.g. an APC or perhaps a truck towing a howitzer) following in the tracks of the first tank drives over it – an event which might occur seconds, hours or even weeks later. The M608 double-impulse fuze is particularly useful when fitted to mines located on the outer edges of minefields, because this gives tanks a false sense of security. The lead tank, for instance, can drive over 30 mines fitted with double-impulse fuzes without detonating any of them. This lures tanks deep into the minefield, where they eventually trigger mines fitted with the M603 or M624 fuze (both of which operate exclusively in single-impulse mode) and become trapped. Attempts to recover the tanks or rescue victims are hindered by the fact that the M608-fitted mines previously driven over are now operating in single-impulse mode, and also because minefields containing M15 mines usually contain various antipersonnel mines as well, for instance the M14 mine and M16 bounding mine. An additional benefit of double-impulse fuzes is that they give mines a degree of protection against clearance techniques which use blast overpressure or mine roller systems. Specifications Weight: 14.3 kg Explosive content: 10.3 kg of Composition B Diameter: 333 mm Height: 150 mm Operating pressure: 160 to 340 kg (for the M603 pressure fuze) Users The U.S.A holds a large inventory of this mine. In 1984 it had approximately 1,904,000 M15 mines in storage, of which around 70% were serviceable. See also M23 chemical mine References Jane's Mines and Mine Clearance 2005–2006 Anti-tank mines Military equipment introduced in the 1950s