Not sure if this is the best forum for this, but here goes...

I'm looking to get the slide on my CZ SP-01 milled and drilled/tapped to mount a micro reflex.
Right now I'm looking at the Burris Fastfire III since I'm on a budget, but may want to upgrade to a Trijicon or a Deltapoint in the future.

Does anyone know if the two mounting screws on these sights are at the same spacing, or if I get it tapped for the Burris, am I locked
into that sight? The spacing looks the same in pictures but I can't find actual specs anywhere.

Thanks.

Ask the manufacturers.

Not all that many people have pin gauge sets needed to accurately measure hole to hole on threaded holes.

Agreed.  I would definitely ask the manufacturer.  They might even send you a drawing.  I would strong suggest that over trying to measure.  Trying to measure it will likely introduce more room for error.