Need help to identify 1911

[Navy Vet]

Hey everybody,
I need help to identify this 1911. I believe it is a Colt commerical government model but am not sure. It has the rampant colt on the back of the slide behind the serrations and it has the patent dates on the left hand side of the slide with the last of them being Aug. 19, 1913. no US property stamp and on the right hand side of the slide it says Colt Automatic and Calibre 45. It also has stamped on the slide and frame what I believe is a serial number 49337 but looks to be hand stamped. Also on the frame above the mag release is a eagles head with S4 stamped below it. I think this is a springfield armory stamp. What can anyone tell me as to the date of manufacture and possible value of this pistol. Is this and arsenal rebuild? A commerical model pressed into military service? I am at a loss on this one as I have never run into this before. Take a look at the pictures.
http://i231.photobucket.com/albums/ee189/Navy1vet/Colt19111.jpg
http://i231.photobucket.com/albums/ee189/Navy1vet/Colt19112.jpg
http://i231.photobucket.com/albums/ee189/Navy1vet/Colt19113.jpg
http://i231.photobucket.com/albums/ee189/Navy1vet/Colt19114.jpg
http://i231.photobucket.com/albums/ee189/Navy1vet/Colt19115.jpg

Thanks in advance for any comments or suggestions.

[Doran]

Military frame and commercial slide but not a genuine rebuild pistol. The USP stamp removed and the number restamped. Not a good item to posses in the eyes of federal and many states laws.

[Constantine-1911]

Nice ol 45.