First introduced during the Interstellar War in 2246, as the M-46A1, the system suffered several design flaws, being particularly error prone in harsh environments. The M-46A2 was an improved version that came about as the result of a redesign begun in late 2247. It is now one of the most respected rifles the UA Military has ever fielded. It now has over a decade of trial by fire in a wide range of environments. 
First Version released, very error prone.
Standard rifle, featuring a common reciever/stock system, utilizes caseless 7.5mm ammo. 14.49 inch barrel
40mm Grenade Launcher that can be slot attached to the M-46. The M504 can operate as a standard grenade launcher, and has alternative ammo for buckshot, crowd-control and flame thrower rounds. An option 200 rond drum magazine is available.
Carbine Version with a 10.4 inch barrel and a foregrip. Optional sound supressor available.