MSC has Hertel spiral points that are an H4..
I was thinking taps for plating, but a quick look didn't find anything
under a #10.
How many of these do you have to fix/modify???
How far over are the male parts? Is it just scale? Did they
damage the treads somehow? Or did they just grow??
A 2.5mm X .45 is a standard tap, and is almost identical to a 3-56, except
for a tiny pitch error of about .0015".. I wonder if the pitch error would
open things up enough for your mating parts to fit.
Here is a bad idea.. Put a regular old #3-56 in an electric drill, and then run
it in and then run it out, take it out, put it back in, rinse repeat... I guarantee
you will open those threads up after a few passes. DO NOT ask how or why I know this.
If you are making the parts from scratch and are rigid tapping, tap once and then do
it again, but start a few thou difference in height.