Thunder

root@atlas-db:~$ cat description.txt

Thunder is a high-damage sniper rifle title for both pump-action and semi-auto rifles. The title itself does not alter stats, but it denotes high base damage compared to other sniper titles.

root@atlas-db:~$ cat notes.txt

Thunder is assigned to sniper rifles with high damage. Pump-action snipers use the Thunder title, while semi-automatic snipers use the Driver title instead, and the name does not affect stats.
From the part naming, a separate Driver title was planned for semi-auto snipers, but those parts still show up in-game as Thunder.