M79 Ammo

M79 ammunition was 40 millimeters in diameter. That's a little less that 1 5/8", and they weigh about one pound apiece.

HE stands for high explosive. HE rounds were used in open areas where the round wouldn't hit a tree and explode early, possibly wounding our own guys. If an M79 man was good, he could shoot through the trees and make the round land on a dime from 300 meters.

A beehive round is like a big shotgun shell.  They were used for close in fighting because you didn't have to aim, just point.