The serial numbering of the inside of the slide began in 1917, c. sn 34000, with just the last 3 digits of the sn. Beginning in 1919, c. sn 40000, the entire sn was stamped insde the slide.

The Colt logo on the left rear of the slide was enclosed by a circle until 1912, c. sn 12000.

The front left side of the slide should read "PATENTED" over "APR201897 DEC221903", both dates, not just the 1897 date.

All slide markings were in serifed letters until 1914, c. sn 18000. At that point, all inscriptions were changed to unserifed block letters, there was also now a period between the patent dates.

 

The Colt logo on the left rear of the slide was enclosed by a circle until 1912, c. sn 12000.

The front left side of the slide should read "PATENTED" over "APR201897 DEC221903", both dates, not just the 1897 date.

73shovel,
EXACTLY the information I needed! Thanks for taking the time to respond and help me out.

 

Looking at your photo, I think that someone, not the factory, has refinished and re-stamped your slide.

The serifed lettering is too small and cruder than factory stamping and all the wording spaced out too much. The Colt logo is too large, not posed and stamped "upright" enough, and definitely would have been enclosed in a circle if the slide was correctly stamped.

I made a mistake in my post above: the patent dates should include periods after APR and DEC and after 20 and 22, no spaces, but periods. Your slide shows no period after the APR, and commas, not periods, after the 20 and 22.

Is the total length of that slide approximately 6 1/2"? Somehow the photo, or more probably, the size of the lettering makes it look longer.

 

73shovel, Your information has been tremendously helpful and I sincerely appreciate you!

 

Here's slide markings on a 1911-mfg'd 1908 for comparison... not the greatest pics but should give you the idea of what 73shovel is talking about.
The periods in the patent date are hard to see but if you squint hard, they're visible LOL.
Also note the barrel is blued along the whole length, including the exposed portion in the ejection port.

 

somd_mustang, I have 1911 production 1908 Model M sn 7046