For many years Otobreda built the Swedish Bofors Weapon Systems 40 mm L/70 air defence weapon under licence as well as improved versions to meet specific defence requirements including land and sea air defence applications.

In 1988, Otobreda announced that it had developed as a private venture, the new 40 mm 40L70N Fast Forty gun which fires at the cyclic rate of fire of 450 rds/min, an increase of 50 per cent over the existing gun.

The 40 mm 40L70N Fast Forty gun is included in the modernisation project for the M42 self-propelled air defence turret and for various other tank turret projects, as of mid-1999, this weapon had not been installed in a complete turret for AFV trials.

According to Otobreda, the substantial increase in the rate of fire is possible because of the intense research and development undertaken by the company, using advanced design techniques such as CAD/CAM through mathematical simulations of the kinematic motions and stresses of the entire mechanism, cold functioning simulations using a specially designed bench with a run out simulator and in live tests on the firing range.

In designing the Otobreda 40L70N Fast Forty gun, use has been made of materials such as titanium. The new design entailed a substantial reduction of the distance run by moving components with a consequent time saving. Valuable milliseconds have been gained, for example, by greatly reducing the recoil length. In addition, a new ramming device has been introduced which allows for the transfer of the round from the feeding position to the breech block closing position, taking a shorter route.

Energy which is made available when firing the gun is accumulated in hydropneumatic linear motors during the return in battery phase. This gives faster, more controllable breech operation which allows optimisation of the requisite acceleration and deceleration. These devices are employed, for example, for the return to battery of the recoiling mass, for moving the ramming device, to decelerate the round immediately before breech block closing, accumulating energy employed to render faster upward movement of the block.

The Otobreda 40 mm 40L70N continues to fire the standard Bofors 40 mm L/70 family of ammunition types including armour-piercing, preformed fragmentation (proximity fuzed) and high explosive types.

According to the installation, the gun can be completed with an automatic magazine holding up to 120 rounds of ammunition in two types, so allowing the gunner to select a particular type of ammunition to engage a specific target, for example, air or ground.

Ready for production. Already installed on Otobreda single/twin naval and field mountings. A turret with anti-aircraft and surface capabilities is currently under development. As of mid-1999, there are no known production applications for this weapon.