A gas assisted spray nozzle assembly having a nozzle body in the form of a one piece hollow tubular member, such as a single cylindrical pipe section, which defines a mixing zone and a downstream barrel extension zone. A liquid inlet and an impingement pin are supported by said tubular member in opposed relation to each other at the mixing zone, and pressurized gas inlet is provided at an upstream end of the tubular member. The impingement pin in this case has an impingement surface radially offset from a central axis of the mixing zone on a side opposite the liquid inlet for receiving pressurized liquid and redirecting the liquid toward the central axis for enhanced intermixing with and atomization by the pressurized gas stream.