FG, FFG, FFFG....used to describe: (PGI May 2011)

Ans: C (Black gun..) FG, FFG, FFFG.... are used to describe the size of grains of black gunpowder.Gunpowder used in FirearmsBlack PowderQ# It consists of Potassium nitrate 75%, Charcoal 15% & Suiph ur 10% (Pnemonic - PCS in decreasing percentage)# It is designated as FG, FFG, FFFG, etc., depending on size of the grains. More the no. of F's, the finer are grains & the faster the burning. The powder grains are black, coarse or fine, without any particular shape. It burn with production of much heat, flame & smoke. The gas consists of CO, CO^ N2, H2S, H2, CH+ etc., alt at a very high temperature.Smokeless powder# It consists of nitrocellulose (guncotton) or nitroglycerine & nitrocellulose (double-base). Triple base powder consists of nitrocellulose, nitroglycerine & nitroguanidine.They produce much less flame & smoke & are more completely burnt than black powder.Semismoke less powder# It is a mixture of 80% black & 20% smokeless powder.