Focus on the pronunciation of big gun
English definition of “big gun”
/ˈbɪg ˈgʌn/ n [C] (also big shot, big wheel,
/ˈbɪg ˈhwil/, /ˈwil/)
› someone who has an important or powerful position: Their lawyer, a big gun from Detroit, commissioned a bunch of surveys to show that their products met the state's standards.