Harrop said police action against organised crime groups had also helped reduce tit-for-tat shootings between rivals.
He pointed to a series of shootings in Derker, in Oldham, between November 2024 and January 2025, which police linked to a dispute over drug territory and which led to the recovery of several firearms.
“Recovering more than 420 viable firearms since 2021 is a significant achievement,” Harrop said.
“While these figures are encouraging, we are not complacent and remain absolutely committed to targeting more offenders who seek to bring violence and fear into our communities.
“Every firearm we recover is a potential life saved.”
The last fatal shooting in Greater Manchester was in March 2023, when Zikel Bobmanuel was killed in Openshaw.
His half-brother, Rumaal Ingram, was later sentenced to life imprisonment, with a minimum term of 16 years, after admitting manslaughter.
Gun crime campaigner Prof Erinma Bell, who founded CARISMA in Manchester, after witnessing a shooting in 2002, said community groups had also played their part in reducing gun crime.