Is the graphics rendering modified to output actual barrel projection to match the display, or did you just take the original perspective projection and stick it on a distorted screen?

Consider making the screen panoramic around a larger radius rather than just around the head, perhaps on the order of ball diameter. This reduces the visual stereodisparity mismatch and lowers the cognitive load for habituation.

Consider also making the trigger chin- or bite-activated to allow simultaneous shooting and moving.