The ribbon used is usually white, or green. It unfurls when the submunition is released and orientates the device so that it falls with its shaped charge facing downward. The ribbon loop vibrates as it passes through the air and this vibration arms the device.
When the device lands in an upright position, inertia carries the firing pin into the stab-sensitive detonator and initiates the device.
If the device does not fall for long enough to unscrew the firing pin, it will not be fully armed on arrival.
If there is any obstruction on the thread of the firing pin, the device may not be armed on arrival.
If the device does not land in the correct orientation or strikes obstructions such as buildings or trees, it can fail to initiate. Its ribbon may catch on obstructions and so hold the firing pin away from the detonator.
Moving or handling an unarmed device can rock the ribbon from side to side and allow it to arm.
Moving or handling an armed device can make the firing pin slide forward into the stab-sensitive detonator.
The M77 can kill. If there is any uncertainty about its state, it should always be destroyed where it is.
The M77 is 42mm diameter and 81mm long:
High Explosive charge: 33 g of TNT/RDX
Anti-armour shaped charge liner
A simple fuze mechanism designed to detonate on impact.
As with all fragmentation munitions, only one person should approach this device at a time.
The M77 is a common threat in Lebanon.
