With the toggle train removed from the pistol, and the striker(firing pin) fully forward and projecting from the bolt face; place the legs of the 1.35mm side on each side of the protruding pin and move it across the pin, the pin should pass without touching-if it does the protrusion is ok; if it touches the pin, then the pin is protruding too much, and should be shortened till it will pass.
Now turn the tool around and use the 1.1mm side, it should not pass over the exposed tip of the striker, if it does the striker is too short.
The striker should have a smooth, rounded tip; in addition to being the correct length.
You can do the test quicker than I can type "how".
