The modern US Army smoke grenade is a signalling device use for air to ground and ground to ground signalling, identification and screen for cover. Developed in 1942 to replace the M16 smoke grenade and designed to produce more smoke in much more vibrant colors.
Both were produced at the same time as the M16 production lines were already setup when the M18 was adopted. The M16 was available in red, orange, yellow, green, blue, violet, and black. The M18 initially were going to be produced in the same colors, including white, but it was decided to limit it to four colors (red, yellow, green and violet) for simplicity. The M16 was declared limited standard in 1944 but was still available when it was declared obsolete in the early 1990s.
When used in Vietnam, the practice was to detonate the M18 , and ask the aircraft to identity the color. A simple security practice to ensure the helicopters did not try to land on an LZ set up for ambushing by PAVN or VC troops or to mislead CAS aircraft into shooting at the wrong position.
|Color/Markings:||Green OD body with a pale green band and markings, the top painted red, yellow, green, or purple to indicate the smoke color and the color’s name marked on the side.|
In World War II the M18 had a light gray body with a yellow band and markings and the top was in the smoke color.
|Body:||Sheet steel cylinder with four emission holes at the top and one at the bottom to allow smoke release when the grenade is ignited.|
|Fuze Assembly:||M201A1 Pull-ring Igniter. A “mouse trap” type igniting fuze with a 1.2 to 2.0 second delay. Ignition ignites the filler and expels it from the grenade body.|
|Filler :||11.5 ounces [326 grams] of a colored smoke mixture. Available in red, green, yellow, or violet.|
|Weight:||19 ounces [538 grams]|
|Range:||Can be thrown 35 meters by an average soldier.|
|Duration:||The grenade produces a cloud of colored smoke for 50 to 90 seconds (0.85-1.5 minutes).|