FG, FFG, FFFG....used to describe -
the synopsis of forensic medicine & toxicology ; Dr k.s narayan reddy ; 28th edition ; Pg.no. 125 ; Black powder is designated as FG,FFG,FFFGetc depending on the size of grains . The more number of F the finer are the grains & faster is the burning .
Primer
Caridge
Black gunpowder
Base of firearms
Mechanical injuries