Tough subject, I too don't have any of the proofs or evidence, a lot of talk of whip but actually measurements are rare (came across it someplace and maybe I can dig up)

So the following links pretty well say what you did, heavier is stiffer. Shorter is stiffer as well. Once contention was that something like 22 inch barrel was ideal. That was 100 yd shooting for the most part but a lot of interesting details came out of it (warehouse in Houston).

http://gunsmagazine.com/good-vibrations/


https://www.shootingsoftware.com/barrel.htm

http://www.stocks-rifle.com/harmonics.htm

My head hurt when done.

It is incredible with all the variations and monkey motion, we can hit and 8"x8" target at 100, let alone get into the half MOA and less, pretty amazing stuff.

If you knew nothing about shooting, and went through all the variables and were then told people can shoot 2/10 inch groups at 100 yds you would say they were nuts.