"Taiwan Panther" The Type 91 Carbine
(T-91A2 Modernized Prototype)
While many contemporary military rifles can trace their lineage back to the AR-18, a pioneering firearm of significant obscurity is the 1969 Colt Model 703, an experimental external piston rifle which sought to replace the M-16A1. While it inevitably failed to secure any military contracts and saw only two prototypes ever built, the 703 would serve as the design basis for the Taiwanese Type 65 in 1976. Though an obscure footnote in the pages of small-arms history today, the T-65 bears the unique distinction of being the first external piston AR platform rifle ever adopted as the standard military arm of any country. A monumental achievement decades before weapons like the HK-416 would make external piston AR's mainstream.
Produced by Taiwan's 205th National Defense Arsenal, the T-65 and its carbine offspring, the T-86 and T-91, both introduced in the early 2000's, remain in service with over 12 countries. In Yemeni military trials, T-91's outperformed the famously reliable AKM in sand burial tests thanks to its short-stroke piston system being entirely enclosed within a steel sleeve, preventing ingress of sand. The T-91 also exhibited many then-futuristic characteristics for a fighting rifle, with quick-adjust illuminated iron sights, a picatinny railed upper, a semi/auto/burst fire control group, and the retention of the AR-15 buffer system, allowing the gas system to be managed simply with a heavy buffer and spring rather than a fragile adjustable piston.
With the United States Army and Marine Corps only recently moving to fully standardize external pistons with the SIG Spear and M-27 IAR, it's amusing to see the United States take such a long path away from direct-impingement and back to external pistons the likes of which had been in service with other countries for decades. While the T-91 isn't a rifle of any particular fame, it remains a fascinating example of an alternate timeline in the evolution of the AR-15. A fantastic rifle that combines the reliability of an external piston with the precision and modularity of the AR-15.