I have been looking at the effects in great detail today, and they are most dramatic to say the very least. For the example I'm using a bullet with a G1 BC of .588 at 3100 fps at 300' ASL, 59 deg F, 29.53 BP. With only 6 degrees of cant, which is only 1 minute on a clock face, at 100 yds it will cause less than .1 MOA POI divergance from POA "with a 100 yard zero". Now, here's where things get worse, much worse I might add, and I hadn't really thought of it until I stumbled upon it when I moved my 100 yd zero out to 750 yds and noticed the chart change by "many, many" inches when I zeroed the wind out and typed in 6 degrees of cant for kicks and giggles. After all, I was looking at 1.0 inch of error at 1000 yards when I was looking at the cant effect on the chart with the 100yd zero, not bad I thought, even though I'd have been holding over some 241" unless I rezeroed for a 1000yd shot. After rezeroing it to 1000yds, man did the cant induced error jump up!! Now at 1000 yards it was 28", up from an inch! Now these are pretty small numbers you might say.... Well, lets put it in perspective a bit more and see just how significant it really is. First, I'll presume without a bubble level, we could realistically be maybe + or - 12 degrees off of of vertical, or canting a couple of minutes off to either side, maybe even more, especially if on a hill or without some sort of visual frame of referance. I do a pretty good job by eyeball at keeping real close to level, and also leveling my scopes on the rifle initially (which is just as important), so I never figured I was off much.... BUT At 1000 yards, with 12 degrees of left cant (2 minutes till ) the program says POI be 56.47" or 5.39 MOA off to the right, and 2.08" or .20 MOA low! Now them numbers are pretty darn significant! 5.39 MOA off on the horizontal is insane! This isn't even mentioning the wind either... The same 12 degrees of cant at a mere 500 yards is going to still kill you by 10.70" or 2.04 MOA on the horizontal, still nothing to blow off. Now, you can see that is close to 1" off for every degree with a 500yd zero, and 4.7" per degree for a 1000 yard zero. With 360 degrees to a circle, a few degrees of cant could easily go unnoticed. Thought I'd share with you what really kind of surprized me, I really thought I'd looked at it closer along time ago... I seen really small error numbers and basically discounted it as a minor effect out to 800 yards or so. A side note. Who knows anything about laser printing a reticle on overhead projector type plastic film, cutting the top half of the reticle off, leaving a half moon type piece to tape to the lower half of the scopes objective bell away from the glass and using it to read mirrage? I'm told the European sniper/tactical competition teams are using it in place of other methods we all know about, and it works much better, as I'm told they're winning all the time with it now?