Hunter:
Yes, a couple of members of the S&WCA have a Database on the AC revolvers. It includes both known legit and known illegitimate examples by serial number. However, it will be of little use unless you can post the entire serial number.
It is also worth remembering that a factory letter is not really a guarantee of authenticity. What a factory letter does is provide the factory data on a given serial number. If the serial number on a gun has been faked then all the factory letter can do is provide the details on that number. It can't tell one if the gun is legit or not, and in the world of Aircrewman revolvers there are, unfortunately, a number of fakes including some well executed examples.
My suggestion is that you post the complete serial and some additional, quality photos of the top strap markings, butt and good shots of both sides. Without those it is very difficult for anyone to say with certainty that the gun is right or wrong.
HTH.