While loved by troops, the venerable ART-18 assault rifle was known to be picky about ammunition, and was somewhat finicky in sandy environments, causing the New Cordian Expeditionary Corps to being trials for a more reliable weapon in 1984. The Corps requested a highly durable rifle suitable for combat in harsh environments, firing their standard 7x40mm cartridge from NICO STANAG magazines, with an action preferably based on the Avtomat Kalashnikova. Castle State Arsenal settled on a license-produced version of the Spreewerkian T3-12 rifle (itself in turn based on the AKM) as the basis for their entry, because it already possessed many of the improvements they needed. Castle replaced the original AK bolthead with a 6-lug AR-15-style bolthead and matching barrel to improve accuracy and better handle the high-pressure 7x40mm rounds, added a modified version of the ART-18A's folding stock, and fitted their weapon with a stamped sheet steel heatshield and polymer handguard. They also devised a railed receiver cover and magazinewell for STANAG magazines. The ART-84 was cheap, accurate and reliable, and could be used with the same magazines, barrels and ammunition as it's predecessor, traits that ultimately lead to it's adoption and use by the Expeditionary Corps. The weapon was so popular that it remained in service until 2013, when it was replaced by the MBR-13 system. The ART-84 is now mainly used as a weapon for reserves and for the civil militia and home guards, as well as some police departments.