I dont even think of shooting before 1,000k. Theres no point wasteing ammo when simple turns will protect you better from such long range fire. In KI-67s I dont shoot till 800 out, and would probably be better off holding off until then in every bomber. The only thing I use long range fire for is for lead according to fighters speed. While I have splashed fighters at 1,000k, most of all Spits, I'll bet most are splashed at 400 to 600k.