Found this:
Grenade, Hand, Smoke, M16 : another type of chemical grenade very similar in size and shape to the M6 / M7 types . Introduced upon demand of the Army Air Corps and Armored Force Command in October - November 1942 . The mixture burned for almost 2 minutes . Here are its main characteristics :
(1) Grenade, Hand, Smoke, Colored, M16 = igniting fuze M200A1 – Sulphur, Potassium Chlorate, Sodium Bicarbonate and dye filler – tinplate smooth cylindrical body - 50 yards range – 2 seconds, full volume after 3 seconds – blue-gray color with SMOKE (COLOR dye), ” lower band, all in yellow color – signal use - approx.use 1943-1944
Remarks : first fuze used was the M200 type . Although introduced in November 1942, the M16 smoke grenade was however quickly declared ‘substitute standard’ due to insufficient smoke volume capability . Initially 8 color dyes were used i.e. blue – green – orange – red – violet – yellow – black – white, later however, blue was dropped – in the end, only 4 basic color mixtures were retained red – yellow – green – violet (while the others were declared ‘obsolete’, but in fact never cancelled) . Grenades filled with colored smoke are mainly used as signals for air-ground and ground-to-ground communication .