Re: What is my problem with my vertical all of a sudden?
With a vertical string like that you're dealing with some major movement that has to be associated with the humidity and stock warp. Some of the other suggestions may help improve a little but not what you're seeing now.
I've competed in 1000yd benchrest for years and groups like this don't come from anything but a major change in, not components but drastic alterations. Outside of doing some stock work your pressures may be a little high but I doubt it. There were times where we had to "bake" our loads under a heating lamp because we didn't anticipate the colder weather, once we got them hot enough they worked out fine. I don't recommend anybody doing this but yours is not the case, it could be you had some hot loads and when the temp rose your load exceeded maximum pressure.
Check your cases and see if you have any signs of pressure and go from there. Out side of that, go ahead with the bedding and make sure the barrel is free floated....good luck
My final authority in all matters of faith and practice is the King James Bible. It's still the monarch of books!!