A Sydney man has been charged over a $2 million drug bust last month that resulted in cocaine and an assault rifle being seized from a fake air conditioning unit.

The 37-year-old is the second man to be charged after Strike Force Raptor detectives raided two homes at Rockdale and two Botany industrial sites in late August.

They allegedly discovered 7.7 kilograms of cocaine and seven firearms - including an assault rifle, a Smith & Wesson revolver and semi-automatic pistols - hidden in a fake air conditioning unit above a penthouse apartment in Rockdale.

A search of the basement uncovered a further one kilogram of cocaine, one kilogram of ice, bulletproof vests, four firearms and ammunition.