I've shot many spinners in PRS matches, but always with precision bolt guns. Making hits with a precision bolt gun is much easier, as most precision rifles are shooting 1" groups at 200 yards. The trick is timing the shot based on the spin of the spinner plates, so I generally shoot as the largest bottom spinner plate is coming down, NOT when the plate is already at the bottom. Your shot time delay will depend on distance to target, and how fast the spinner is spinning, and with some practice, you will start to see when you need to brake your shot. Also, it's generally better to shoot the bigger bottom target, as it's heaver with more momentum, and you will usually get the spinner all the way around quicker.

I would assume 200 yards with a 14.5" AR with M193 would be tough, as most ARs are shooting 2-4 MOA with M193 ammo, vs .5 MOA with a precision gun. Also, a 55 gr .223 bullet is not going to move the spinner like a bigger 6mm, 6.5, or .30 cal bullet will, so it may take more hits. That being said, it's probably very possible to do with an AR, but will take some actual practice on a spinner. Hope that helps a little