I'm not sure if this is the best forum, but I couldn't find anything
better suited.

I'm looking for some metric 2.5mm shoulder screws, and I've been
calling around and Googling for days unable to find them. It's for an
RC car, and the only ones I can find at hobby shops have a slightly too
long shoulder. I need some with 4mm shoulders, and all I can find are
5mm shoulders.

Does anyone here know where I might be able to find them?

I also thought about buying a 2.5mm die and just re-threading about a
millimeter of the shoulder, reducing its length. Does this sound
reasonable?

I have never used a die before. Would it be feasable to put the small
screw in a vise or pair of locking plyers and use the die, or would
that just deform the head of the screw from tension?

Thanks,
--Farrell F.