QTD-33

The QTD-33 Anti-Material Assault Rifle is the standard issue assault rifle which the Quantonian Empire use.
Known for its reliability and accuracy the QTD-33 has been used in the Empire for over 500 years, It has a multi-slot magazine chamber so it can fit from 50 Caliber sniper round to a simple pistol round.
The rifle was mass produced on the 13/06/2578
Its tight fit parts make it durable,steady and even accurate. Pretty much every part of the weapon is deconstruct-able so it can be repaired and replaced.
The QTD-33 is one of the very few outdated and still fully functional weapons.
The QTD-33 can have a lot of attachments ranging from scopes to grenade launchers and even internal upgrades such as customized increase rate of fire.
The QTD-33 still uses the classic gunpowder based bullets which keep the weapon cheap and easily manufactured. 
The QTD-33 can shoot 900 rounds a minute.
The QTD-33 does not use electrical components meaning that if there is an EMP the gun wont fry.
The QTD-33's multi-mag size slot gives the rifle an ability to transform from a Assault rifle to a High caliber marksman rifle.