Shit, I am such a sucker for dialog-driven character exposition. Fucking gorgeous piece, really.
(One teensy, tiny, technical nitpick: As a person who is firearms trained IRL (short-range semi-automatic pistols, and 1000+ yards bolt-action rifles), in order to slow the pulse rate and steady the trigger finger, the shooter exhales when the trigger is engaged. Inhaling speeds up the heart and pulse rates, which significantly degrades accuracy.)