The square area framed by the osti and wirble gunsight is 180Mil wide. In the osti that makes for a good lead sight against drones out to 1200yds, I was just testing it. The gunnery terrain helps you alot to spawn up on the mesa and use the lead computing cross to see this. After that, your shooting becomes problematical and better against on coming or leaving flight profiles. The dispersion of the 37mm in the osti is your problem at longer ranges and why it always works better against bombers 1200-2500. And max range in the game is only 2700.