Try setting your Preferences>General>When Scaling: to Apply to Content
Thanks for the suggestion. I found that the one thing that works is to use the "redefine scaling as 100%" from the top pull down menu. This is what I do to get rid of the parentheses on the font sizes and I didn't realize it also needed to be done on the line weights as well. My hope was to find a simple way to create a scaled down document that automatically gives the correct measurements, but so far this is the best I can do. A bit cumbersome, but at least it works.
The preference has changed a bit with the CC apps, but this is what I see in CS6:
With Apply to Content selected, the stroke is scaled and the transform percentage stays at 100% after the scale, so a 300% transform shows the stroke starting at 10pt and ending at 30pt with the scale value reset to 100%
With Adjust Scaling the stroke size is unchanged, but the transform percentage is indicated, so here I have a 10pt stroke, but its scale is 300%. Changing the preference only affects future transforms