IMR meaning in Military and Defence ?

Improved military rifle propellants are tubular nitrocellulose propellants evolved from World War I through World War II for loading military and commercial ammunition and sold to civilians for reloading rifle ammunition for hunting and target shooting. These propellants were DuPont modifications of United States artillery propellants. DuPont miniaturized the large artillery grains to form military rifle propellants suitable for use in small arms. These were improved during the first world war to be more efficient in rimless military cartridges replacing earlier rimmed rifle cartridges. Four-digit numbers identified experimental propellants, and a few successful varieties warranted extensive production by several manufacturers. Some were used almost exclusively for military contracts, or commercial ammunition production, but a few have been distributed for civilian use in handloading. Improved military rifle propellants are coated with dinitrotoluene (DNT) to slow initial burning and graphite to minimize static electricity during blending and loading. They contain 0.6% diphenylamine as a stabilizer and 1% potassium sulfate to reduce muzzle flash.