The Pindad SB1 assault rifle is a dedicated law enforcement weapon, produced by the PT Pindad (Perseo) company in Indonesia. It is used by the local police forces, including the Sabhara (Satuan Samapta Bhayangkara) “public alert” unit which perform patrol and public security functions across the country.
The story of the Pindad SB1 rifle began in the late 20th century. At the time Indonesian police used a significant number of US-made .30 caliber M1 carbines, which by late 1980s were well worn out and obsolescent. However, Indonesian police authorities felt that the moderately powerful .30 Carbine ammunition was well suited for the local Police needs, and it was decided to locally procure a new automatic rifle, somewhat similar in its ballistic properties to the old M1 Carbine. The task to design and produce such rifle was handled out to the local arms manufacturing company PT Pindad.
First, the Pindad engineers developed a new cartridge, known as the 7.62x45mm MU11. It is based on the 5.56x45mm NATO cartridge necked up to accept a round-nosed 7.62mm bullet, so it can fit easily into the action of the gun originally designed for the 5.56mm ammunition. From the 363mm (14,3”) barrel this cartridge accelerated its 7-gram (108-grain) bullet to the muzzle velocity of about 560 meters per second (~1835 fps). Later on, a specialized “anti-riot” less lethal 7,62mm MU11-K cartridge was developed. It fires a lightweight 0.5 gram (~8 grain) plastic projectile with muzzle velocity of about 315 m/s (1030 fps). There also exist the 7.62x45mm blank rounds used to launch the tear gas grenades from the muzzle of the rifle.
With the cartridge on hands, they then slightly redesigned the 5.56mm Pindad SS1 military service rifle for this new type of ammunition. The redesign consisted mostly of installing a new 7,62mm barrel, replacing the full-auto capability of the trigger unit with the three-round burst mode, and designing a proprietary magazine.
The Pindad SB1 assault rifle is a gas operated weapon. It uses a long stroke gas piston system and a rotary bolt locking with a Kalashnikov AK-style two lug bolt.The upper receiver is made from a stamped steel, and the lower receiver appears to be machined from some sort of a light alloy. Rifle can fire single shots or three round bursts, and uses a proprietary magazine with a standard capacity of just 13 rounds. Standard iron sights have two settings, for 100 and 200 meters, which is considered enough for the police / security use. The Pindad SB1 rifle is produced in two basic versions, with barrels 363mm (14,3”) or 254 mm (10”) long.
Pindad SB1 assault rifle, basic specifications