well, AK-47 were named type 56 submachine gun* is because it was imported and copied in 1956. but SKS, as type 56 semi auto rifle was the standard rifle for the force back then. when it's 60s, type 63 was issued, it was an auto rifle. later it was proved no good in services and soldiers thought it "wastes bullets too much". so in a 12 men sqd, sqd leader and vice sqd leader uses type 56 submachine gun, and 8 rifle men with SKS, 1 machine gunner and 1 feeder. rpg may be in some of the units. in 1979, bullets rain were throw on PLA, as they realized the importance of the fire rate, and as claimed in the books " everyone took a type 56 semi into the battle and as they returned, almost all SKSes were claimed lost and with brand new AK-47s in hands"
type 63s were reissued later in 1979, but were retired forever from the service very soon. and type 56 submachine gun became the standard rifle after the war of 1979. until type 81 were tested in battle of lao shan.
*type 56 submachine gun. as people may notice that i said submachine gun instead of "assualt rifle" or "automatic rifle". In china, back then, people only recongized two types of automatic weaponary, machine gun and submachine gun, it could be an inflence of PPSh-41/43 submachine gun. To difference both type 56s, one was caled type 56 semi auto rifle another was called type 56 submachine gun.
Most of the AK shaped rifle in the war of 1979 were captured viet namese weapons.