The 40 mm 40/70Ba gun has been developed by Bofors Weapon Systems as the main armament for some members of the Swedish Army's Combat Vehicle 90 armoured vehicle, the first production contract for which was placed early in 1991. First production vehicles were delivered to the Swedish Army in October 1993.

Variants of the Combat Vehicle 90 armed with the 40 mm 40/70Ba gun are the Mechanised Infantry Combat Vehicle (CV 90 40) and the anti-aircraft (CV 90 AA). In both cases the weapon is mounted in a two-man turret designed and built by Bofors Weapon Systems. Additional details of the Bofors Weapon Systems turret are given in the AFV turrets and cupolas section.

For trials purposes, the complete CV 9040 infantry fighting vehicle turret has been fitted onto a stretched Polish MT-LB and a Polish BMP-1 chassis. The latter version is called the BMP-40 (or BWP-40) in Poland. Early in 1998, for trials purposes, the CV 9040 turret was installed on the Swiss MOWAG (10x10) Armoured Combat Vehicle chassis which has already been adopted by the Swedish Coastal Artillery as a command and control vehicle.

The Bofors Weapon Systems 40 mm 40/70Ba is based on the ordnance of the 40 mm L/70 towed anti-aircraft gun which is loaded with clips of four rounds of ammunition from above with the empty cartridge cases ejected via a chute in the forward part of the weapon.

The 40 mm 40/70Ba is inverted with the fixed ammunition fed from the bottom. The cartridge cases are ejected upwards and forwards through a hatch in the turret roof.

Under the breech is the magazine which is divided into three eight-round compartments. Each compartment is loaded with one type of ammunition. The change from one compartment to another is by a hydraulic device; changeover time is two to four seconds. Ammunition is loaded into each of three magazines manually and it takes 60 seconds to load 24 rounds.

The Bofors Weapon Systems 40 mm 40/70Ba gun can fire single shots, two, four or eight-round bursts or full automatic. It can fire the following types of ammunition: APFSDS-T with a muzzle velocity of 1,480 m/s, 3P (prefragmented programmable proximity fuzed) with a muzzle velocity of 1,012 m/s, PFHE Mk2 (prefragmented high explosive proximity fuzed) with a muzzle velocity of 1,025 m/s, MPT (multipurpose tracer) with a muzzle velocity of 1,025 m/s and HE-T (high explosive - tracer) with a muzzle velocity of 1,025 m/s, TP-T (target practice -tracer) with muzzle velocity of 1,025 m/s and a target practice round for APFSDS-T with a muzzle velocity of 1,500 m/s. This has the same ballistic performance out to 1,500 m as the actual APFSDS-T round.

Production. In service with the Swedish Army installed on the CV 90 vehicles