Gundam alternate calendars usually taking place in some indeterminable far future, but not everything from the old era is gone. Sometimes, traces and remnants remained, even thrived into the new era.
Zastava Arms is one such survivor in the Cosmic Era. Founded in 1853, this company made cannons, mortars and guns. Into the Cosmic Era, Zastava start to dabble in mobile suit weapons manufacturing, creating the Zastava-Stigmate RFW-99 beam sub-machine gun.
The RFW-99 is used on the Eurasia Federation's Hyperion series mobile suits, a (failed) competitor to the Atlantic Federation-Orb's G-project mobile suits.
Unlike the MS weapons of the G-project, the RFW-99 has removable battery pack instead of drawing power from the MS itself. The weapon is also equipped with a beam knife. Though its output per shot is lower than its G-project counterparts, it possess higher rate of fire.