Not much of a concern with screws, only hex nut sizes.The only caveat is that they're likely metric or some Euro / German standard that doesn't match my tools.
I'll find out tomorrow morning...
For screws get a good gunsmith screwdriver set. It has sizes for about anything you can come across.
https://www.midwayusa.com/product/4...professional-plus-gunsmithing-screwdriver-set
If I gave a gun back to a customer with boogered screw heads after a trigger job, he'd shoot me with it. LOL