Re: Horizontal drift due to bullet spin and drop?
If there was 6 MOA of drift with no detectable wind, was the rifle canted? was the scope adjusted? If so, is the scope level? Between spin drift, coroilis, a canted rifle and/or a scope that is not level and adjusted to -0- at 1K could easily account for 60 or so inches.
Spin drift alone should not be more than 9-12" fired from a 308 at 1K
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.