The 5.56mm Combat Standard is the most common intermediate rifle cartridge in GLMZ 2200 by volume, which is either a testament to the round's genuine utility or a self-reinforcing market reality depending on who you ask. Its lineage runs directly to the 5.56x45mm NATO round that equipped most Western military forces from the late 20th century through the mid-22nd, when caseless intermediate cartridges began displacing it in formal military use. The 'Combat Standard' designation was applied by the GLMZ Civilian Munitions Board in 2178 to distinguish conventional brass-cased loads from caseless variants — the brass-cased version is still the dominant commercial product because the weapons that chamber it are cheaper, better-understood, and maintained by people who learned on them. The projectile has been updated: standard commercial loads now use a copper-polymer composite bullet with a hardened steel penetrator insert that exceeds the capability of the old green-tip military loads.

In GLMZ 2200, 5.56mm Combat Standard is democratic in the way that only truly common things can be. Tier 1 gray zone workers in the outer boroughs buy it for the rifles they keep in back rooms. Tier 3 security contractors use it in the same platforms their grandfathers used. Excluded communities in collapse zones stockpile it because the rifles that eat it are everywhere and spare parts are available at any salvage market. Arcturus Civil Security uses it in patrol carbines. It is simultaneously the most mundane and most politically charged round in common circulation — because a cartridge this available, this capable, and this affordable represents a specific kind of power that certain interests would prefer to see concentrated rather than distributed.