Trigger Stop
Below is an exact copy of the information on the KTOG site and is provided
here for your easy reference.
Named after Bill White, this
trigger stop is simple, cheap and recommended to improve
control and trigger recovery speed. Take a standard #2
pencil eraser and cut it in half yielding two cylinders.
Glue it to the back of the trigger with Crazy Glue or
epoxy about 1/8 to 1/4 inch down from the set pin. Before
gluing make sure the eraser clears the sharp edge on the
grip frame where it engages the frame or it will be
damaged over time. An alternative location is to mount
the stop on the frame itself where it will engage the
trigger. We have tried both locations and each works
well. Trim and shape the eraser with a small file or
emery board. Adjustment is done by filing the eraser
until the "break" occurs just as the stop
engages. Dry firing with sights on a clear target will
enable you to see if the Trigger Stop forces you to
squeeze to hard. A well adjusted stop will give you a
staged feel when it engages, yet not cause a move off
target when pulled through to fire. The stop enables you
to stage the trigger and improve control on the first
shot. Double taps will occur faster because of the
trigger's reduced over travel. For cosmetics, apply black
magic marker to the eraser and it blends in perfectly
with the gun making it look factory original. This is a
great low cost modification that has no downside. Simple,
cheap, easy, safe. If the trigger stop falls off, the gun
will still fire in an emergency. This is a highly
recommended modification that anyone can do.
Now, what I have to add.

I prefer to mount the stop to the grip, as
shown in the picture. I also prefer to adjust the stop so
that there is no staging of the trigger. So you do not even
notice the stop until after the trigger breaks. These are
just personal preferences, I make no claim that they are
better than the alternatives.

I like to use a black eraser from a mechanical pencil as
shown in the picture. I think it looks better than a marker
colored eraser and the color never wears off. Unfortunately
Bic has started making these pencils with white erasers and
the black ones are getting difficult to find.
Having installed a dozen or more stops for friends, I have
found that the required thickness varies widely from pistol
to pistol.
With your pistol unloaded, pull the
trigger and observe the gap between the rear of the trigger
and the frame as the trigger breaks.
Cut a piece of eraser slightly thicker than the gap you
observed. File/sand it down until you can get the trigger to
break by squeezing the stop a bit when setting in place.
(pointing at the ceiling allows the stop to sit in place.
Glue the stop in place by cleaning both surfaces with
rubbing alcohol, allowing to dry and using a drop of super
glue.
Final fit by filing/sanding the stop until you reach the
desired release point. You may wish to hold the trigger
lightly against a strip of sandpaper while you drag it across
the stop to shape it to match the trigger. (Make certain the
trigger breaks easily each and every time you pull it, do not
leave the stop so thick that it is difficult to fire)
If you feel you filed/sanded off too much, you can put a
drop of super glue on the stop to build it up a bit. (don't
pull the trigger until the glue dries completely) If it still
is not to your liking, rip it off and try again.
Test fire to verify reliability.