Flechette
From BattleTechWiki
Flechette ammunition is a special munition that can be used by standard autocannons. Engineered to be effective against conventional infantry, it is composed of metal fragments instead of explosive shells.
Introduced by the Federated Suns in 3055 to improve the effectiveness of their autocannon, the usage of flechette munitions reinforces the importance of autocannons to that nation.
Flechette rounds deal double damage against unarmored infantry in CBT play, though they deal half damages against all other targets.

