 Rifle Grenade blank cartridges, M1 (1933–1945), M2 (1941), M3 (1941–1953), and M3E1 (1953–present): These cartridges are used in conjunction with the M7 series of rifle grenade launchers to propel rifle grenades. Blank cartridges utilize a full-size brass case and carry only a powder charge.  M1, M2 and M3 blanks are sealed at the case-mouth with a red wad and the M3E1 is crimped. The differences between the three cartridges have to do with the powder charge and the range of grenade launchers. The M1 was a universal blank and rifle grenade cartridge that replaced the specialized rifle grenade (RG), chemical rifle grenade (CRG), and chemical warfare grenade (CWG) cartridges and was used with cup-discharger rifle grenade launchers. The M2 was an experimental cartridge used as a testbed; it used a propellant mixture of black powder and smokeless powder because it was feared that the smokeless powder would not reliably ignite by itself. The M3 was designed to be used with the M1 series (for the M1903 Springfield rifle), M2 series (for the M1917 Enfield rifle), and M7 series (for the M1 Garand rifle) spigot grenade launchers and used a propellant that was a mixture of five grains of FFFG black powder and 40 grains of IMR-4898 smokeless powder. The M3E1 featured an extended case neck, a rosepetal crimp, and a full smokeless powder loading and was designed for use with the M7A3 spigot rifle grenade launcher and larger ENERGA rifle grenade. The grenade blanks were issued in double-rowed 10-round cartons, usually as part of a set with the hermetically-sealed metal M13 grenade launcher assortment ammo can.