If someone can place three shots in a one inch circle at 100 yards with a .30/06 - 150 grain Remington Core-Lokt bullet, at what type of distances will the logic that leads one to come to the conclusion that he can place three shots in a 2 inch circle at 200 yards, a 3 inch circle at 300 yards, etc. hold up as long as the shooting is done under good conditions (from a rest on a nice, clear day)? This is assuming that that person isn't experienced at shooting at longer ranges. I don't have any way of shooting at longer ranges to test it for myself and I am curious. Is this a difficult question to answer?

Good question. I wish there was an easy answer. Basically, yes, if all things are equal and there is no wind, a 1MOA group at 100 yards will remain a 1 MOA out to some distance. At what distance the group starts to fall apart depends on just about every factor imaginable. My old .30-06 would shoot anything at 1MOA out to about 350 yards and then some loads held a group and some fell apart. My Savage 10FP in .308 will shoot 190 SMK's at 1MOA at 1K. 168 SMK's start to have issues at a little past 400 yards. The best I have been able to figure is the rate of twist is a little fast for that bullet, from this barrel, at this velocity. Too many hunters find good loads for 100 yards and never test them at distances they wind up hunting at. I let my rifle and load tell me what the limit is. My best 100 yard load isn't always my best 1000 yard load. I'm not sure what recommendation I can make if 100 yards is the longest you can practice at.

It can easily come apart at distance. Having a range of 150 fps difference will not matter for vertical dispersion at 100 yards, but becomes much more significant at longer distances. Ballistic coefficients start to rule at longer distances and a 150 grain Core-Lokt is not likely to behave as well as a match grade bullet. The best way to answer your question though is to shoot at those distances. If asking because of an intent to hunt at those ranges you need to have verified and practiced at those distances before going afield.