Shawn, thanks for taking the time to share the info in on this, I just about went crazy when I first started shooting 1000+. I was shooting a 50 cal. with 750 A-maxs. The combo shot pretty well and would group decent but it would hit dead on at 100 yds, about 3 in right at 600 and the longer the distance the worse it got. I had never heard of spin drift at the time and I thought I must be canting the rifle or the reticle wasnt plumb or some other error I was committing. I bought a base level, got everything plumbed and had the same problem only a little worse. I then noticed the 300 ultra was doing about the same thing just not as bad. Yep, the 308 does it too. I discussed this with quite a few people and was told everything you can imagine. Most said it was caused by undetected wind, some said I just couldnt shoot, many went into great detail about how I wasnt getting a good cheek weld or I needed to curl my little toe on my left foot just prior to breaking the trigger. I began to think it was because I was born naked when I was a baby. Finally I came to the realization that something was causing the projectile to drift to the right. I would get up early in the morning and tie little white feathers from the posterior of a chicken all up and down the range, located where they could be observed while engaging the targets at various ranges. What I learned cost a young fortune, Shawn just got through telling everyone in less than a minute what took me a year, a barrel, and who knows how much money to find out. A pure target shooter will never figure this out, because he will go to the range, shoot a sighter, and correct for windage. The rest of the day will be spent compensating for changing conditions. This works great for their purposes but for someone needing to make first round hits on littlebitty things way out there, spin drift is definately part of the equation. I agree with the gentleman in the prior post, a program that could figure this out for every round loaded with every make, shape, or form bullet would take some doing; however any individual can sort this out without a lot of pain for the combination he is shooting. Do the numbers that Shawn posted and see if they are significant in your situation. If not, dont worry about it. If you are shooting at game 800+ you should know how much it affects you and compensate for it. By Shawns numbers it effects my 300 ultra about 7 1/2 inches at 1000. This is very close to what I have seen. That in itself is the difference in a clean kill and a good day gone bad.