window frame advice needed.

Beware hardware store screws. The screw that is used there is not standard.
If you are making new screw holes you can make smaller than factory holes and use a #6 screw.
If you are reusing the original screw holes a#8 screw is required. The head on the standard $8 screw is too big and will not let the trim in the clip. Some have bent their trim trying to get it in the clips where the screw head interfered.