The TR-116 was a rifle developed in the 2370s by Starfleet Security to operate in energy dampening fields or radiogenic environments, places where a phaser would not function. The rifle used tritanium bullets that were propelled chemically. Although design schematics were drawn up and replication patterns kept, the project was abandoned in favor of regenerative phasers.
In 2373, the USS Budapest was one of five test-bed starships that had TR-116 rifles aboard. When the Budapest engaged the Borg at the Battle of Sector 001, Sam Bowers and other crewmembers used the rifles against the Borg, killing many of them and stopping them from assimilating more members of the crew. Bowers had to also use the rifle to kill his assimilated crewmates, including Captain Sh'Raazn.
In 2375, Lieutenant Chu'lak, unstable due to the loss of his friends aboard the USS Grissom, replicated a TR-116 rifle on Deep Space 9. He also made modifications to it, adding a micro-transporter and an exographic targeting sensor device. He killed several crewmembers with the rifle before being stopped by Ezri Dax, who also used a TR-116.
The crew of the USS Enterprise used TR-116 rifles during their peacekeeping duties on Tezwa. The rifles were said to be able to shoot through walls, indicating that Chu'lak's modifications were later adopted and standardized for use in the field. They also used its sister weapon, the TR-120 .
In 2381, the crews of the USS Enterprise and USS Aventine used TR-116s to defeat Hirogen boarders. TR-116s were also used in a battle to seize control of a Borg interceptor.
By 2410, the TR-116 was renamed the TR-116A while a new version, the TR-116B, was fielded. With the advent of personal deflector shields, the TR-116B was designed to penetrate through them fully.