That's exactly what you would do, but you'll find that with some fine twisting and turning each way, you might find that the A/O isn't lined up with the 200yd mark. This is because of each individual's eye changes and how well calibrated the scope is, and that is usually in the scope's cost---but not always, as even some of the cheapest scopes(which I have a few) out there may be on the mark, with some luck. Basically the A/O takes out blurred images and seeing more than 1 crosshair(parallax) from 20yds to infinity to help you see the target clearly for the yardage used and is only a helping tool, so if your scope's A/O markings are slightly off, don't fret it and just get a clear image before pulling the trigger. This helps you with knowing if your gun/rifle is able to take the shot by needing to use hold-over, or putting the crosshairs dead-on. The A/O also helps the shooter sight in their scope by giving some indication with it's clarity, just how far from a target they are, when you don't have a lazer yardage monoscope. I use A/O all the time when sighting in my scopes to make sure I'm at least on paper at 10yds and make some adjustments(if needed) then back up to 25yds(readjust A/O) take a couple shots, and if still good, then I'll back up 50 to 200yds depending on scope and rifle. Of course some of my scopes don't have A/O because they're parallaxed(closely) for a certain yardage of 50(more like 20 to 65yds),75(between 60 to 80), or 100yds(more like 85yds and beyond), so I use a lazer sighting device to give me actual yardages then work my gun to it's, and my capability. Some folks will use a 2-7x32 without A/O scope for hunting from 25yds to 150yds and not worry about parallax(I don't) because it'll still kill the animal, and surrounding hunting obstacles(trees/brush and no wide open spaces) prevent the usage of high powered scopes impractical, while other folks will use a 8-32x50 scope with A/O for target shooting at 25 to 100yds to see where their bullets are precisely hitting for competition, where just .002 of an inch means you're the winner or the loser of match. Also be aware that with (some) scopes that have A/O, or even power magnifications, the scope's POI(point of impact) could change, and this is usually associated with scope's cost, reliability, and where made. Any other questions, feel free to ask.