Howdy,

I have a target made up in Word for getting a 300M zero on the ART II at 100 yards...  POI should be 5.6" high at 100 yds (175 SMK at 2580fps.)

I don't have the POI at 25 yards handy, and unfortunately I'm on the road and don't have my Sierra Infinity ballistics CD with me.  I can tell you though that by my measurements the ART II in the Government Model M14 mount is 2.07" above the bore centerline.  With that info you should be able to plug into any decent exterior ballistics app and get a rough POI for 300 meter zero at 25 yards.

Just a warning though- because of the mechanical nature of the machined surface of the cam, the zero of an ART II will vary up and down +/- 1MOA or so through its travel between 3 and 9.  Also, the curve of the cam may not exactly match the ballistics of the ammo you are shooting.  Because of these variables, I recommend the following approach-

First get a very rough "on paper" setting at 25 yards.  (Notice I didn't call it a "zero"...)  Then get a rough zero at 100 yds.  This will save you some ammo and frustration and at least have you on paper.  During these first two steps, you should mostly be keeping the reticle centered and be using the adjustments in the mount to get you near center.

Then, as time and range facilities allow, move out to 300 meters and see where you are.  Because of the possible variations between your ammo/rifle ballistics and the cut of your particular cam, even a good center zero at 300 meters may have you off by feet at 900 meters.  300 is only 1/3 of the designed operating range of the scope.  At this point you should only be making moderate adjustments to the windage and elevation dials on the scope itself if you have adjusted the mount properly.

Next you want to get a solid zero at about 80% of the max range you will ever shoot.  If you want the scope to work out to 900 meters/1000 yards, I would suggest you get a good center zero at around 750/800 meters.  This will split the difference between the trajectory curve of your ammo and the machined curve of your cam, and should minimize the +/- errors of the machined cam surface.

Last and final phase, shoot the rifle at all ranges between 300-900 meters, keep good notes, and make fine adjustments to split the difference of cam errors so that when you are just shooting fast in autorange mode, your will never be more than 1 MOA or so above or below POA (depending on how your particular cam was cut, and what ammo you are using.)

I have a metric ton of technical info compiled on the ART II and its cams, send me a PM and I'll send it all to you.  As a matter of fact I still owe that package to a few other members and haven't been able to send it due to bandwidth issues, but I'm in a good spot now and might be able to get it sent out.