I'm wandering off into long range pistol & rifle shooting. My goal is to hit a 18" square target consistently at 1000 yards. Seems like any serious shooter is using a ballistic calculator on their phones. Done a little research and there are dozens of them, some free and others that cost some money. Any recommendations? Must be Android friendly because I ain't gonna buy a new phone just for this. Obviously free would be a plus but wouldn’t mind spending a couple of bucks for something that works well.