Lots of Operation Eldest Son vibes. MACVSOG really instilled primal terror into the VC with their handiwork, far more than even the B-52 flechette carpet bombings. To not know whether your AK is gonna turn into a crossbow pointed pointblank at your own forehead or not with every shot you fired REALLY fucked with the VC's ability to operate to their full potential for quite some time.
The Eldest Son rounds were actually a charge of polymer explosive, a chemically enhanced version of C4 or RDX that was able to be initiated to full detonation by a blasting cap small enough to fit into the primer of a 7.62 case, so the damage it did to an approximate 2 foot circle around the cartridge, including the enemy operator's head, was catastrophic.