In 1984, design work on an indigenous 40mm automatic grenade launcher was begun in Spain by Empresa Nacional Santa Barbara as a private venture. Adoption by Spanish forces followed in 1992 (as the SB 40 LAG, also written as "SB LAG-40") through an initial preproduction batch of sixty units. The weapon is a contemporary to the American Mk 19 and the Soviet/Russian AGS-17 which have permeated global inventories concerning portable grenade projecting devices.
The SB 40 relies on the long recoil principle which reduces stresses exhibited upon the frame. It makes use of a roller locked system and is chambered for the global standard 40x53mmSR projectile firing from a 24- or 32-round belt. The belt is sat within a hard ammunition case that can be mounted to either the left or right side of the receiver as required (changing requires some internal modification of the system by the user). The weapon achieves a rate-of-fire of 215 rounds-per-minute at a muzzle velocity of 787 feet per second. Available iron sights allow for sighting between 100 and 1,500 meters while grenade effectiveness reaches up to 2,000 meters. Attack angles can vary from line-of-sight to indirect fire as needed, making the SB 40 a flexible tactical weapon. The system is typically fielded on a heavy duty, adjustable tripod though it can also be mounting onto vehicle, watercraft and helicopter pintle mounts.
Outwardly, the SB 40 takes on the appearance of the American Mk 19 with its decidedly rectangular receiver, spade-type grips at the rear and short barrel assembly at the front. Sights are affixed across the top of the receiver in the usual way and a cocking handle controls the feed/bolt during the initial charge. Dimensionally, the SB 40 is a large weapon despite it being portable and it weighs upwards of 75lbs, features an overall length of 38 inches and sports barrel of 16.3 inches long.
The modern Spanish military utilizes the SB 40 as a support weapon at the infantry level and has mounted it atop their various four- and six-wheeled armored vehicles as well as tracked armored personnel carriers. The major issue variant is recognized as the "40 SB-M1". Columbia remains the only other notable operator of the SB 40 system (as of 2013) for it has accepted a stock of SB 40 grenade launchers for mounting onto their navy patrol boats.