Carter doesn't use a gun. He uses a chillingly calm psychological breakdown of his opponents' weaknesses and a demonstration of "calculated force" to dismantle the threat without breaking a sweat.
(Carter leans forward, his voice dropping an octave. The room goes dead silent.) [S9E7] Carter the Enforcer
Based on the title "[S9E7] Carter the Enforcer," Episode Logline Carter doesn't use a gun
The threat is neutralized, but the team now looks at Carter with a mix of awe and fear, wondering who exactly has been sitting at the desk next to them for nine seasons. Scene Snippet: "The Change" [S9E7] Carter the Enforcer