The Striker 9 is a submachine gun available in Call of Duty: Modern Warfare 3 (2023)
The damage improvements come from the Striker Elite Long Barrel and although it reduces movement speed, the CS15 Cylindrical Laser, XTEN Phantom-5 Handstop, and Lachmann MK2 Light Stock ensure move around the map and aim down sights as fast as possible.
Lastly, the Sakin ZX Grip provides some much-needed recoil control allowing you to use the Striker-9 at longer distances in addition to close-quarters combat.