RE: Mossberg 835 trigger
I've never had an 835 down, but if they are similar in design to their 500 series, I'd say not without a competent gunsmith.
The hammer spring in the 500 is integral within the trigger group. Short of working down the sear engagment surface, (which I don't advise), the only way to lighten the pull (on a 500), would be to install a softer main spring. Ahh, but that could lead to unreliable ignition of your primers.
It seems to me that the newer guns all seem to come with a built in attorney. His name is always "Trigger" and he weighs anywhere from 8 to 14 pounds. Safety first is their motto, but often at the expense of a crisp, clean pull. [&o]