@David Johnston, what do the sizes represent, shank diameter of the rivets to be used with each tool, or the diameter of the pointy little head of each tool? Or...?
@gunrunnerjohn, " I find it easier to set the small rivets with that tool than with the press, at least for me." Totally agree, especially after bending almost every single coupler knuckle rivet I tried! Haven't tried that again in years!
@harmonyards, And Pat, thanks for the tip on "light greasing of the rivet and tool" prior to clinching. I will try that on my next "larger than a coupler knuckle" rivet job.
And finally, back to my original question, is there a published guideline that says e.g. that if you are trying to clinch a 1/8" diameter rivet you should use a 0.125" tool? I know that seems like a pretty basic question, but I have never seen it answered anywhere 
George
