Factory specs for the Trooper Mark III were....
Single action minimum.....3 pounds, maximum....5 pounds.
Double action maximum....14 pounds.
Due to the surface hardened action parts no polishing is possible because of cutting through the thin case hardened finish, ruining the part.
In any case, since the parts are molded, not machined, the action parts are already as smooth as will do any good.
To improve the trigger pull a lighter mainspring and a lighter trigger return spring can be installed.
Wolff Gun Springs sell spring kits.