Building on lessons learned from manufacturing the underwhelming M75 and M59 APCs, the FMC Corporation designed the M113 and started production less than four years after being awarded the initial development contract.
The resulting vehicle is essentially an aluminum box on tracks. The front hull slopes back and is mostly covered by the trim vane, which can be extended by hydraulics when the vehicle needs to enter deep water. Behind the trim vane is a hatch which allows access to the engine compartment, containing the water-cooled V-8 gasoline engine. To the left of the engine is the driver’s seat, from where he can use an overhead hatch or the four periscopes surrounding it in order to see where he is going. A near-infrared periscope (grants Night Vision 4 when used with the infrared lamps on the front of the hull – see GURPS High-Tech, p. 47) can also be fitted to the hatch. A small floor access hatch below the drivers position could be used to escape in an emergency. In the center of the hull is the vehicle commander’s hatch, which has an external open mount for a Browning M2HB machine gun (GURPS High-Tech, p. 133) and five periscopes. Below and behind the gunner is the troop compartment, which has one central seat facing backwards and folding benches suitable for seating five facing inwards on either side. The roof of the troop compartment has a large rectangular hatch, from which a few of the passengers can view their surroundings, or shoot. At the rear of the vehicle is a large ramp which opens onto the troop compartment. Set into this is a small door, allowing egress if the ramp mechanism fails.
A medium radio (GURPS High-Tech, p. 38) is mounted behind the driver, who also has an intercom (GURPS High-Tech: Electricity and Electronics, p. 27) to speak with the commander. A telephone connector at the rear of the vehicle allows wired communication. A manually operated vehicular fire extinguisher (GURPS High-Tech, p. 229) is mounted next to the radio and could be activated from inside or outside the vehicle.
Despite doctrine stating that the M113 was not a fighting vehicle and should be used only to convey troops to suitable fighting positions, during the Vietnam war it was often used aggressively in the light armor role. Although this was generally an effective tactic against poorly armed opponents, it required the crew and passengers to expose themselves to enemy fire. In order to make this a little less hazardous, improvised gun shields were added around hatches. This was soon formalized as the Armored Cavalry Assault Vehicle (ACAV) upgrade and official kits were issued in 1963 which added two side panels and a gun shield to protect the gunner from all sides except above, and gun shields which could be fitted to the new machine-gun mounts on either side of the passenger hatch, intended to work with the M60 (GURPS High-Tech, p. 134) carried by the infantry. All of these provide DR 18. The ACAV was usually manned by five – driver, commander, two M60 gunners, and a grenadier with an M79 grenade launcher (GURPS High-Tech, p. 142). The passenger seats were removed to provide room for more ammunition and supplies.
The first major modification to the design was to substitute a more powerful diesel engine for the gasoline one and enlarged fuel tanks. The steering system was also improved to allow tighter turns at low speed or in water. The new vehicle was designated the M113A1 and arrived in 1964. Optional extras included a fire-suppression system (GURPS High-Tech, p. 229), and an air-filtration unit which could connect to gas-masks.
In 1979 the M113A2 added numerous small improvements, including better engine cooling, stronger torsion bars, and moving the fuel tanks out of the passenger compartment. Two four-barreled smoke dischargers (GURPS High-Tech, p. 229) were added to the front of the vehicle. Many existing vehicles were upgraded to this standard. The introduction of the Mk 19 MOD 3 automatic grenade launcher (GURPS High-Tech, p. 143) offered an alternative to the commander’s machine gun.
The next round of upgrades, in 1987, was the change to the M113A3 standard, which further improved the steering, replaced the engine with a more powerful one, added more fuel tanks, and protected those inside with spall liners (add DR 10 to occupants and negate the special effect of HESH warheads) and NBC filters.
Several applique armor kits have been made. Mine protection plates add DR 20 to the underside and increase weight by 0.5 tons. Side armor panels add DR 50 to the sides and 1.3 tons to weight, which reduces top speed by 1 and makes the vehicle unable to float (remove note [1]). A cage of slat armor makes the front, sides, and rear count as having spaced armor (GURPS High-Tech, p. 229), and adds 0.1 tons of weight.
DRIVING/TL (TRACKED)
| TL | Vehicle | ST/HP | Hnd/SR | HT | Move | LWt. | Load | SM | Occ. | DR | Range | Cost | Locations | Notes |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 7 | M113 | 108 | −3/5 | 10f | 1/18 | 11.8 | 1.6 | +3 | 2+11 | 60/50 | 200 | $150k | 2CX | [1][2][3] |
| 7 | M113A1 | 110 | −3/5 | 10 | 1/18 | 12.3 | 1.6 | +3 | 2+11 | 60/50 | 300 | $170k | 2CX | [1][2][3] |
| 7 | M113A2 | 110 | −3/5 | 11 | 1/18 | 12.4 | 1.6 | +3 | 2+11 | 60/50 | 300 | $190k | 2CX | [1][2][3] |
| 8 | M113A3 | 113 | −2/5 | 11 | 1/20 | 13.5 | 1.7 | +3 | 2+11S | 60/50 | 300 | $210k | 2CX | [1][2][3] |
[1] Amphibious: water move 1/2.
[2] Fire extinguisher.
[3] Higher DR is for front, lower DR is for sides, rear, and top. Underside has DR 40.
