The Berger range of "marginal" is wider than any other I have seen. I expect it is because they are trying to allow for people to go into colder conditions, or maybe for some lots of bullets to be longer than average. But several authorities from Harold Vaughn to Don Miller put stability factors of 1.4 to 1.5 as best for benchrest accurracy, while Berger is calling them marginal. I would have to ask to learn what their reasoning is. A Sierra tech told me long ago that gyroscopic stability factors of 1.3 to 3.0 are best for hunting accuracy and 1.4 to 1.7 was best for match accuracy.
Today you can get away with higher numbers for match shooting than you once could because bullets are made better and with more perfectly uniform mass distribution. Berger may be counting on that, but again, I'd have to ask. But check the calculator on their site or at the JBM Ballistics site or at Geoffrey Kolbe's site for a somewhat more comprehensive approach based on McGyro. Use your velocity and your atmospheric conditions and measure and use the length of the longest bullets in your box.
