While guerrilla warfare certainly played a role in Vietnam, the Viet Minh / Viet Cong / NVA had more at their disposal that just small arms. Where it counted, Communist forces had firepower aplenty, with which in the year 1954 they blasted the French army into surrender at a place called Dien Bien Phu.
Dien Bien Phu French Defeat in Vietnam. - YouTube
Some 15 years later, American forces met a similar situation at an outpost called Khe Sanh.
Battlefield Vietnam - Siege At Khe Sanh - YouTube
During that best-forgotten war in South East Asia, the United States and its allies were not defeated by just the AK-47 alone. (In fact, amongst the Australian forces deployed there, most of the casualties were inflicted by landmines and booby traps).