Are you wanting to call them in, or are you hoping/trying for long range shots from the vehicle type of thing?
In my experience, 500 yd sight ins with the 223 means you'll likely overshoot anything that you call in to normal ranges or even see within normal ranges.
Shooting them from the vehicle is very low percentage kills IME, that is why I began calling some 24 years ago. Problems associated with shooting from the truck (even though it is fun
, and sometimes we get one
) is that they usually have already seen us and will be running shortly. If we take the time to range the dog, dial the correction, dope and hold for any wind, and get a solid rest; the coyote usually has already got nervous and is quickly leaving the area. What I am getting at is; We're usually only given running shot opportunities . Often times, as soon as a vehicle stops, they are running and not about to stop for a shot. ...................That's been my experience in most parts of Wyoming anyway.
Additionally, if they are close enough that you dont' have to worry about ranging them (well under 500 yds with any load), then we want to be able to hold on hair for elevation and only concern ourselves with lead for moving targets and holding for a little wind..........therefore, my first suggestion, no matter if you call them in or shoot them from the truck; is to sight in your rifle for dead on at about 200-250 yds. That way you're holding center mass from the muzzle out to about 250-300 yds.
I've put some other tips in this thread, more directly related to calling:
http://www.longrangehunting.com/forums/f30/calling-sequence-question-new-hunter-84225/
Best of Luck.