Actually, the de-resonator does work--but often only under the exact same conditions you "tune" with it. This is because most ammunition varies somewhat at different temperatures, and some barrels even vibrate differently.
This is also the problem with any other barrel-vibration tuner. In my experience it's better to work up a load and TEST it at various temperatures with a standard "resonating" barrel to see what happens.
I may be prejudiced, as well, by one experience with the de-resonator in the field--not by me, but a guy I ended up in camp with on an elk hunt in Colorado. He was what I call a "double-number" hunter, as in "I shot a 327 bull at 486 yards."
He had de-resonators on both his rifles, and would tell anyone within hearing distance how great they were. On that hunt he missed a cow at 150 yards.
