Here in the land of the free we can own all sorts of fun guns.
HELI-HOG'N on Vimeo
This guy takes it to the extreme. This is all legal.
This Texas feral hog shooting chopper video (LOACH on the job) is fascinating. The pilot has a fixed rifle with optics rigged back to his helmet and eye-piece. He doesn't miss and his scout-chopper flying skills are down pat with the hogs behavior and pack or group running style. This came from Greg Cooper who has a huge ranch SE of Brownfield, Texas... south of Lubbock. I don't know where the chopper hog hunting op is but it is clearly West Texas. I don't see them dropping flags or stakes from the air to ground-mark their kills so as to go find them easily but I assume they "know" the country or wait for the turkey buzzards to tip them off. The pilot is really good!