Tubes and primers are used to ignite the propellant in projectile weapons.

The Ordnance BLC 15-pounder gun was a modernised version of the obsolete BL 15-pounder 7 cwt gun, incorporating a recoil and recuperator mechanism above the barrel and a modified quicker-opening breech. It was developed to provide Territorial Force artillery brigades with a reasonably modern field gun without incurring the expense of equipping them with the newer 18-pounder. It is the gun that writers usually mean by "15-pounder gun" in World War I, but can be confused with the earlier Ordnance QF 15-pounder Ehrhardt or Ordnance BL 15-pounder, both of which fired the same shell.