The First Order's predecessor, the Galactic Empire, had stormtrooper snipers. When the Empire surrendered at the Battle of Jakku in 5 ABY, many Imperials fled into the Unknown Regions and joined the First Order. The First Order created their own Stormtrooper Corps, and trained stormtrooper snipers.
First Order stormtrooper snipers wore typical stormtrooper armor and primarily carried DLT-19D heavy blaster rifles, though they were also able to wield IQA-11 Blaster Rifles, A280 blaster rifles, NT-242s, and Cycler rifles. Sergeants wore black Pauldrons.
First Order stormtrooper sniper Sergeants appeared in multiplayer gamemodes in Star Wars Battlefront II as the Specialist class for the First Order.