 Also, modern soldiers rely a great deal on vehicles and helicopters to transport them around the battle area, and a longer weapon can be a serious hindrance to entering and exiting these vehicles.Development of lighter assault rifles continued, matched by developments in even lighter carbines.In spite of the short barrels of the new assault rifles, carbines variants like the 5.45×39mm AKS-74U and Colt Commando were being developed for use when mobility was essential and a submachine gun wasn't sufficiently powerful.