At the same time, some watches were never actually made. Collectors will often refer to these watches as Frankens, as in Frankenstein, where someone may have re-cased a movement and dial in a non-Hamilton case, or assembled a complete watch using various parts of authentic models.
Personally, I think Frankens are interesting since you can come up with some nice looking designs and as long as all the parts are authentic you could de-franken them if you wanted - so no harm done. I'm not a big fan of Hamilton dials and movements in private label cases masquerading as authentic models though - to me those are just spare movements waiting for a new home. That's more common with ladies models than with mens but you will come across both fairly often.
There are many Hamilton watches that were not cataloged. Usually they are "presentation watches" provided to employees to mark service anniversaries. In fact, Hamilton had a separate awards division to cater to this important business segment. Part of the intention of not cataloguing these watches was because customers did not want their employees to see their "award watch" for sale in their local jewelry store.
I recently purchased a 1960's Hamilton Automatic in a stainless steel case. As received, it was pretty beat up but running so it made for a nice project watch.
Identifying a Hamilton model is a two-step process... First you note the case material and design details like the shape of the lugs, along with the dial details like the hour markers and printing.
The Second step is to go through the myriad catalogs and look for a match. I like to use the "resource center" on an online forum I participate on... check it out by clicking the link below if you need to identify a Hamilton watch.
Once I pulled the beat up crystal, I was able to remove the dial and movement. Both were in very nice shape and appear original to my eye. A little bit of rust on the hands was the only distraction.
Since the stainless steel cased is marked Hamilton Watch Company, it's an authentic case. Knowing the details of the dial, I then consulted the catalogs.
I was able to narrow down my new addition to two possible models, but neither is an exact match.
First is this 1960 Automatic K-304. Note the numerals and markers match, as do the hands and the printing of the Hamilton logo and Automatic. Only problem is the case is yellow gold, not stainless steel, and it looks like the case has a step around the circumference where my watch's case is smooth.
Going into the catalogs a little further, I found the Accumatic VIII. Case shape and material matches, the hands look right. Just the Hamilton logo is a little different and the markers and numerals don't quite agree with my model.
So what model is it? I don't know for sure. Sometimes the catalog images were "artistic representations" of the model - so it's possible that it's an Accumatic VIII, but that's a tough call and a long shot.
One thing is for sure though. Now that it's all cleaned up with a fresh crystal it looks great.