You may want to read up some on the "timing" of a semi-auto pistol. What you are talking about doing is completely changing the timing. Essentially, redesigning the gun. It would involve experimenting with and changing the sear spring, the mainspring, the recoil spring, and the magazine springs. That could lead to other changes with the bolt design. You would also have to minimize the disconnector travel and rework the hammer/sear engagement surfaces.
A crisper lighter trigger and speed hammer (less mass, more acceleration) help the rate of fire, but unless you have a few extra guns lyin around to experiment with, I think I'd leave the timing of the gun as Bill Ruger designed it.
Now the cheap and dangerous way is to highly polish your sear. This can make the hammer slip and you can go into full auto. When this happens, you don't have control of the trigger after the first shot because the hammer is following the bolt forward and in theory, it should keep shooting until the mag is empty.