Military

M77 Scatterable Anti-Personnel [AP] mine

The M77 AP SCATMINEs are cylindrical in shape. They are 6 centimeters high and 12 centimeters in diameter.

M77 AP SCATMINES are delivered using the M131 Modular Pack Mine System (MOPMS)

Cylindrical AP SCATMINEs kill enemy soldiers through the combined effects of blast and fragmentation. Each mine contains 540 grams of composition B4 as its main charge. The charge detonates upon actuation and shatters the mine's metal casing to produce shrapnel. Shrapnel is propelled upward and outward from the mine and produces fatal casualties to a distance of 15 meters.

Each mine has eight trip wires (four on the top and four on the bottom) that deploy after ground impact up to 12 meters from the mine. Trip wires are similar in appearance to very fine thread; they are olive-drab green in color and weighted at the free end. A tension of 405 grams applied to one trip wire is enough to create a break in the electrical circuit and cause the mine to detonate.

Though all SCATMINEs have a similar life cycle, specific times vary based on the SD time and the dispensing system. For safety reasons, SCATMINEs must receive two arming signals at launch. One signal is usually physical (spin, acceleration, or unstacking), and the other is electronic. This same electronic signal activates the mine's SD time. Mines start their safe-separation countdown (arming time) when they receive arming signals. This allows the mines to come to rest after dispensing and allows the mine dispenser to exit the area safely. Mines are armed after the arming time expires. The first step in arming is a self-test to ensure proper circuitry. Approximately 0.5 percent of mines fail the self-test and self-destruct immediately. After the self-test, mines remain active until their SD time expires or until they are encountered. Mines actually self-destruct at 80 to 100 percent of their SD time. The time period from when the mines begin to self-destruct and when they finish is called the SD window. No mines should remain active after the SD time has been reached. The probability of a live mine existing past its SD time is 1 in 10,000. Any mines found after the SD time must be treated as unexploded ordnance (UXO).

The SD time for the M77 is 4 hours (recyclable up to 3 times). As such, M77 mines actually start self-destructing at 3 hours and 12 minutes. When the 4-hour SD time is reached, no unexploded mines should exist.