155 BONUS is a 155 mm artillery-launched fire-and-forget munition developed in cooperation between Bofors of Sweden and Nexter of France, designed for a long range, indirect fire top attack role against armoured vehicles (armored personnel carriers, infantry fighting vehicles and main battle tanks). Compatible with the majority of existing artillery guns, BONUS is handled just like a conventional shell. When launched from any 155mm artillery system, the BONUS carrier shell separates to deploy two sensor-fuzed munitions that then search for targets within a given footprint, up to 32,000 square meters. BONUS is currently in use by several countries, including Finland, France, Norway Sweden and United States.
Each BONUS munition weighs 6,5 kg, has a diameter of 138mm, and is able to pierce out to 100mm of armor. The munition also features a base-bleed design, which increases its range to a maximum of 35 kilometers when fired from a NATO L52 gun. The BONUS base bleed carrier shell contains two submunitions, which descend over the battlefield on winglets and attack hardened targets with explosively formed penetrator warheads. While descending, the submunition rotates, scanning the area below with multi-frequency infrared sensors that compares the detected vehicles with a programmable target database. The submunitions each contain a high-penetration EFP warhead for use against main battle tanks.
BONUS is very similar to the German SMArt 155 (Suchzünder Munition für die Artillerie) system; SMArt 155 descends on a parachute rather than a system of winglets. The United States developed the similar M898 SADARM (Sense and Destroy ARMor) system (which also descended on a ballute to attack the top surfaces of armoured vehicles), but this was discontinued in favour of the GPS guided M982 Excalibur round. US artillery largely deploys the M712 Copperhead laser-guided round for the anti-tank role. By carrying two smart munitions within the BONUS shell, its mission success per round is far greater than with traditional ammunition.