T91 assault rifle The T91 assault rifle ( ) is produced by the 205th Armory , Ministry of Defense , Republic of China ( Taiwan ) . It is based on the proven T86 assault rifle incorporating features from the M16 and AR - 18 rifles with more modern features . The T91 is lighter and shorter than the T65 it replaces and has a 6 - position telescopic stock to allow adjustment based on individual requirements . History . T91 was a further development of the T86 assault rifle which had been intended to replace the T65 assault rifle series in ROC military service . Experience on the previous design and feedback from various users were incorporated into the T91 . Development was completed in 2002 , and volume production commenced in 2003 . Design . T91 is a gas - operated short - stroke , air - cooled , rotating bolt , magazine - or drum - fed , select - fire , modularized military rifle compatible with various tactical accessories . Similar to its predecessor , T91 is a shorter version of the T65K2 assault rifle , giving the operator higher mobility and ease of aiming in confined space . T91 has a 4 - position selector switch : S – safe , 1 – semi - automatic , 3 – three - round burst , and A – automatic . Like the T65K2 , T91 utilizes an M16A2 - style front post , rear peephole sight . The rear sight , mounted on the detachable handle , is adjustable for windage and elevation . Operation of the charging handle , magazine release , and bolt release are the same as the M16 . One notable difference is that the T91 does not have a forward assist , and the brass deflector is not as pronounced . The action of the T91 is based on the T65 series . However , parts are not interchangeable because the bolt lug on the T91 is shorter by 1 mm . T91 also inherits the modularized gas piston system from the T86 , allowing easy removal for maintenance without the risk of losing small parts . The telescopic stock on the T91 was designed based on the experience of military and police personnel with the M4 Carbine . The resulting product has improved recoil transfer and handling qualities . A rubber recoil pad is also added for comfort . The handguards are triangular in shape T91 has a barrel with flash suppressor . Rate of rifling twist is . Due to the use of a shorter barrel , the T91 has 20 % more recoil than the T65K2 . Average group size at 175 m ( 191 . 4 yd ) also increased by . The chamber and bore are chrome - lined and can fire all 5 . 56x45mm NATO ammunition . Standard - issue 30 - round magazines for the T91 feature indicator holes for the top 2 - 15 rounds as well as two protrusions on each side to avoid over - insertion . However , standard STANAG magazines may also be used . Accessories . T91 has a MIL - STD - 1913 rail on the top of the receiver , handguard , and the front - sight block . The standard - issue detachable handle may be removed to accommodate a variety of optical sights and scopes . T91 can also be equipped with the T85 40mm grenade launcher to serve as squad - level fire support . The Chung Shan Institute of Science and Technology developed a T91 indoor shooting simulator for infantry marksmanship training . This equipment is capable of simulating various weather , shooting distance , and wind conditions . Paint ball conversion kit also provided for training purpose . Other attachments are red dot sight s or holographic weapon sight s similar to EOTech . Production and Usage . In 2003 , the ROC Army ordered 101 , 162 T91 combat rifles as force - wide replacements of all service rifles , with a delivery schedule from 2004 to 2008 . The total budget amount was NT $ 1 , 803 million ( US $ 54 . 6 million ) , placing the unit price at about NT $ 17 , 800 ( US $ 539 ) . As of April 2006 , nine ROCA armored , mechanized infantry , and infantry brigades have fully converted to the T91 . In 2005 , ROC Military Police ordered 12 , 069 T91 combat rifles to equip garrison units in the Taipei capital region . Delivery would span over the next three years . Export sales of the T91 to Jordan and Kuwait have been officially confirmed . The Jordanian Defense Forces had reportedly conducted comparison tests between several service rifles in a desert environment . The T91 is found to have reliability comparable to the AK - 47 , while scoring better than M16 , and it is very dependable in desert conditions . Indonesia procured as many as 10 , 000 T91 combat rifles from Taiwan to equip police and border patrol units . The UAE acquired T91 rifles after Sheikh Hamid bin Zayed Al Nahyan made a visit to Taiwan , and soon quantities of T91 were supplied to the UAE . There are rumors that arms dealers had secretly inquired about the possibility of sales to certain militant groups in Southeast Asia , but were reportedly rejected by MND . MND did not confirm nor deny such rumors .