Suspects tried to flush cash down toilets as police carried out raids targeting criminal gangs.
Eight properties in Tameside, Oldham and Rochdale earlier, focused on criminals suspected to use vulnerable people’s homes to stash drugs or weapons – a practice known as “cuckooing”.
Warrants were executed simultaneously at the properties at 05:00 GMT on 19 March, with drugs and £70,000 recovered from the homes, as well as firearms and a zombie knife.
Ch Supt Shan Nasim said: “Organised criminals exploit vulnerable people and blight our communities. We will take robust action to catch offenders.”