Well, Larry, it's me again.  Here's what I do when I need to match
old screws.  First, I go through my boxes of old screws to see if
I can find a match.  If they are old manufactured screws, that
sometimes works.

Second, I go to the store and buy some new screws of the correct size.
I try to get some with the same number of threads per inch.

Then I put the screw in the lathe and remove the plating using a fine
needle file and 400/600 wet-and-dry paper.  Then I polish the head, if
necessary, on a buffing wheel.  If necessary, I can clean them off with
lacquer thinner and dip them into chemical bluing.  You can get this
from the gun department of K-Mart or from a gun store.  Wash off the
excess and buff with a soft cloth and you have a nice blue screw.

Have fun.
Craig Smith
Rochester, New York, USA