User blog comment:Callofduty4/Modern Warfare 3 Spec Ops shown at Late Night with Jimmy Fallon/@comment-4128371-20110614213146/@comment-93.141.6.247-20110615063134

Yeah it's the M9 sound. Notice how all the guns in the SP gameplay have the exact same sounds like their counterparts in MW2. They got 5 more months to change it, anyway.