SAR 21 The SAR 21 with the attached Round Corner Firing (RCF) module Type Bullpup assault rifle Place of origin Singapore Service history In service 1999 -- present Used by See Users Production history Designer Tuck Wah Chee and Felix Tsai of Chartered Industries of Singapore (CIS, now ST Kinetics) Designed Manufacturer CIS: 1999 -- 2000 ST Kinetics: 2000 -- present Produced 1999 -- present Variants See variants Specifications Weight SAR 21: 4 kg (8.82 lb) SAR 21 GL / M203: 5.3 kg (12 lb) SAR 21 P - Rail: 3.6 kg (7.9 lb) SAR 21 MMS: 3.5 kg (7.7 lb) SAR 21 Light Weight Carbine 3 kg (6.6 lb) Length 805 mm (31.7 in) (SAR 21, SAR 21 40 GL / M203, SAR 21 P - Rail) 680 mm (26.8 in) (SAR 21 MMS) 640 mm (25.2 in) (SAR 21 Light Weight Carbine) Barrel length 508 mm (20.0 in) Cartridge 5.56 × 45mm NATO Caliber 5.56 mm (0.22 in) Barrels Single barrel 1: 12 '' and 1: 7 '' twist options Action Gas - operated, rotating bolt Rate of fire 450 -- 650 rounds / min Muzzle velocity 970 m / s (3,182 ft / s) (M193) 945 m / s (3,100.4 ft / s) (SS109) Effective firing range 460 m (M193) 800 m (SS109) Feed system 30 - round detachable box magazine; proprietary or STANAG magazines Sights 1.5 x or 3x optical sight; back - up iron sights
what is the back up sight used in sar 21 in the event of optical scope failure
iron sights