The assault carbine is a magazine-fed, compact automatic weapon with a high rate of fire and a comparatively low spread. It is one of the most accurate automatic weapons in the game, and can be effectively used in close and medium range combat. In V.A.T.S mode, it will shoot a 5 round burst for a cost of 20 action points.
The assault carbine uses 5mm rounds, boasting an armor piercing effect of -10 DT, and 5mm AP rounds, which have a -25 DT effect. These make the weapon highly effective against medium armored or heavily armored targets, as only power armor possesses more than 25 DT. In addition, 5mm HP rounds have only a x2 DT multiplier, compared to the x3 multiplier of other HP rounds. (All effects as of patch 22.214.171.1242). 5mm ammunition is available in large quantities, as it is also used by the high-capacity minigun.
The assault carbine can be equipped with an extended magazine, identical to that used on the regular Marksman carbine except with a black rather than aluminum finish.