The tungsten balls are designed to penetrate materials that haven't been named yet; but I will bet a few bucks that APC's are one of the targets.

The flechette round was used by gunships, artillery in direct fire mode (think Fire Base Crook) and the Sheridan ARV in Viet Nam. In reality; the "dart" was an ordinary nail with fins stamped in one end instead of a head. Some armies have developed actual darts that are supposed to keep a tighter pattern but they are a waste of money IMO. If you fuse the canister to burst at various distances; you can nail a bad guy to a tree. Not very practical; but extremely effective psychologically.

The 152MM Sheridan gun was a favorite of the troops in VN because it could clear foliage as well as people. The round wasn't just large in diameter, it was long enough to carry a load of darts. Unfortunately, a mine could take it out easily and the engine exhaust wasn't designed for elephant grass etc.

The link shows a series of videos of the vehicle in action.

<link>