How to use keyevent for Gun Movement

Hi,
I have made my robot where i defined keys for power button instead of
using Mouse movement i want to use buttons for Gun.

But i am facing problem with Gun.How to set my gun direction
independent of Body to use buttons key for example


if pressed Vk_U = move 180 degree clockwise
if pressed Vk_I = move 180 degree Anticlockwise


Please need suggestion for developer.