BattleMech Manual (p. 84)
A ’Mech can be equipped with mounted weapons that can be jettisoned in combat and—if recovered—remounted on that ’Mech with ease. This feature can be seen in early Star League-era attempts to develop handheld weapon mounts, such as on the BattleMaster
, and Phoenix Hawk
The quirk is bought for a single weapon; a ’Mech can carry a maximum of two jettison-capable weapons, paying the quirk cost each time. It is assumed that any official variant replacing a jettison-capable weapon with another weapon in the same location also uses a jettison-capable weapon, though a gamemaster may rule that variants based on field refits or low-tech conditions do not benefit. No Handheld Weapon or item using pod technology may benefit from this quirk, though fixed weapons on an OmniMech may be jettison-capable.
A jettison-capable weapon may be dropped using the Dumping Ammunition rules, except no risk of hull breaches is created, and no risk of an explosion if a ’Mech jettisoning its weapons is struck from the rear. Jettisoning an ammunition-dependent weapon does not also jettison its ammunition. Treat any critical slots for a jettison-capable weapon as a Roll Again result if they are struck after the weapon is jettisoned.
In campaign play the location of a jettisoned weapon should be tracked, as it can be remounted on the ’Mech later using the same rules and time spent as an ammunition reload. A jettisoned weapon may be used by any ’Mech that is a variant of the ’Mech the weapon was originally designed for, as long as the variant features that exact weapon and in the exact same location.