Carrying two of the hardest hitting weapon available, the Autocannon 20, even an Atlas will second guess an encounter with a King Crab. Backing up the autocannons is a Large Laser for medium range combat and an LRM 15 for some long range reach.
All three variants come with the same stock weapons configuration. The differences lie in the hardpoints. The -000 has the most ballistic, the -0000 has the most energy and missile, and the -000B is right between the two.
An assault 'Mech that can "cripple or destroy another 'Mech in one salvo" - General Aleksandr Kerensky
The King Crab KGC-000 is the most ballistic-heavy variant, with three ballistic hardpoints in each arm. In exchange, it has the fewest number of energy and missile hardpoints.
The King Crab KGC-0000 combines a four missile and four energy hardpoints, in the left and right torso, respectively. In exchange, it has the fewest number of ballistic hardpoints, one in each arm.