I think there is an explanation on the first page of the document and IIRC it is interpolated data.
By the way I have some limited data for the 6X45 with the new AR Comp powder that I worked up if someone is interested.
Very interested in your data as I am a big fan of AR Comp in my 223. Currently considering the 6mmx45
I used 25.0 gr and the load was mild and pretty slow 2700fps with 70gr bullets but shot very well.
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"Anyone taking up handloading necessarily plays with unknown factors and takes chances. But so does anyone who drives a car,goes to a cocktail party,eats in a restaurant,or gets married."
Jack O'Connor 1963