Blast-Fragmentation rounds are the most common
type of mortar and howitzer munitions. They are of little value against
tanks and other armored vehicles because the random shell fragments cannot
penetrate even thin armor. However, Blast-Penetration rounds could cut
through light armor. Rather than blasting into a hundred fragments, they
would fire several darts in all directions to penetrate light armor several
meters away, including tank rear armor and metal road wheels. 
Blast-Pen rounds may consist of small shaped warheads which fire a small anti-armor penetrator dart, like the two used by the TOW2B (right) and BILL "fly-over/shoot down" missiles. Perhaps small anti-armor gun rounds, like the .50 cal SLAP, could be manufactured with two "Siamese" heads. These rounds could be stacked within a cargo shell which would fire them a foot off the ground. Each Siamese round would offset the recoil of its partner as the same explosion sends a bullet in opposite directions.
Another candidate is the 40mm M433
High Explosive Dual Purpose Cartridge designed for penetration; depicted below by
G2mil in actual size for a 155mm cargo round which could carry at least 10
siamese 40mm submuntions. A thin priming tube with explosive filler would
run vertically through stacked rounds to a nose fuse and fire them simultaneously.
This is not a complex or high cost idea,
but the results may revolutionize the battlefield. Howitzers or heavy
mortars could devastate armored units with Blast-Pen rounds. The Swiss
have just fielded a similar weapon 
for
120mm cargo mortar munitions, which contain an amazing 32 sub-munitions per round.
(right)
Carlton Meyer editorG2mil@Gmail.com