I think your original question has been answered in that there is no consitent grading system between manufacturers or suppliers. If I may - and I know it wasn't your question - I'd like to talk about how I choose wood.
First, I need to see the piece, having no faith in the grading systems you reference. This is one of the reasons I often favor used guns.
The first thing I look for in a blank is integrity. Voids or bark inclusions are a red flag because there is no way to know how deep they go or in what direction. The wrist, in particular would be best if grain is parallel instead of across the wrist - and no knots etc there.
The next thing I look for is contrast because without contrast, any pattern is invisible. Might as well use construction lumber.
Pattern is a multi character thing. The patterns (they've been described above) should appeal to you. It should be relatively dense. Compared to furniture, a gunstock is a relatively small canvas to show off what you've got. The other part of pattern maybe the hardest to find. It should be of even character, density and color on all four sides. It's rare for a pattern to be awesome on on one side and also 2 1/2 inches away on the offside. The wood should impress from your view - from the offside where squadmates see it - from the underside as seen in rack and from the topside where it warms your heart a bit every time you mount it.
As an aside, Stock blanks are a bit like a trophy buck. When you see it, you won't have to wonder if "That's the one."
I apologize again for drifting off your original question - but my point is that those grading systems, however they are used, are largely unhelpful.
Rob!
This is my family Christmas picture. I consider two of these to have exceptional stocks. Two others are nice and make me proud. The one on the left is a nice gun, SP1, that comes out on rainy days or when someone want to borrow.
