Ignition - The initiation of burning, either of a priming compound or a propellant.


IHMSA - International Handgun Metallic Silhouette Association.


Improved - Term used to indicate a standard cartridge case which has been altered by fireforming to reduce body taper and/or increase shoulder angle. Improved cases have greater powder capacity than the corresponding standard case.


IMR - Abbreviation for "Improved Military Rifle," a trademark of DuPont (now IMR Powder Company) to its line of single-base rifle powders.


Ingalls' Tables - Ballistic tables computed by Col. James M. Ingalls and first published in 1918. The most widely used ballistic tables in the U.S. prior to the development of computers.


IPSC - International Practical Shooting Confederation.