I'm lost wturri78. Are you trying to fit an aftermarket plate to the Q5 or the one that was included with the Q5?
Mine's a SF but the screws that Walther included worked fine to mount the Vortex/Burris/ Doctor plate.
When you say too wide, are you sure you've got the correct plate? Vortex does not supply the screws to mount the plate to the slide. Walther supplies those. Vortex supplies the screws to mount the optic to the plate
I have a Viper on mine now. Waiting on myself to make a decision between 3 of the newer optics.