I got two new sniper rifles from the gold key chest. One has about 7000 base damage. The other is E-Tech "consumes 2 ammo per shot" and has a little over 10000 base damage. When I test fire them (noscope headshots) at the dummy the 7000 base weapon does about 110k damage. Sometimes it also causes elemental damage over time. The 10000 base weapon does about 70k for the same shot.
The only thing I can think of is that my One Shot One Kill skill does not count on the E-Tech weapon, presumably due to "consumes 2 ammo per shot". I have 5+4 points in that for 108% bonus damage.
(sadly the 7k base damage weapon is Dahl and thus burst while zoomed)