Indeed! Just a few thousandths, so it should be be easy to use your sandpaper on a flat surface technique.
That brings up a concern I have though... Over the course of this thing, there have been changes to the way I do things. The negative contact, button flanges, and even the positive contact have been different thicknesses, I've pretty well standardized things these days,...but up until now, I've always had the mod in hand, so I could make any necessary adjustments...
Long story short,...if folks want me to make and ship them these solid silver retrofit contacts, there may very well be some "fitting" involved, to make it fit the mod your putting it in, just right, as far as being flush with the bottom of the mod, and having the button throw you want...