I have recently had the unique opportunity to work with, disassemble, clean, a un-messed with WWI Colt manufactured 1911. The serial is 2838**. The right side of the slide is marked "MODEL OF 1911.U.S.ARMY". So this pistol was produced prior to the "black army" pistols but it still exhibits some rather rough machine work where careful finishing doesn't matter.
The first two characteristics of this pistol that leaped out at me were that the firing pin stop was squared off at the bottom as is the currently the rage in some circles (to return to the 'original' design like JMB intended and to soften recoil) and the 19 vertical slide serrations on either side of the rear of the slide (only) are plenty sharp and not only aggressively 'grab' the bare fingers but do so to gloved hands as well. I don't remember this as being true of the well-worn 1911A1s I had in my arms room but I suppose I could be mistaken.
I also noted the small sights but they aren't really new to me as all the 1911A1s we had in service had very similar sights.
I, being a bit of a curmudgeon, like the flat main spring housing and don't mind that it is smooth. I have put flat MSHs on my own Colts. I can get along with the long blued steel trigger but I do prefer the shorter 1911A1 trigger.
This gun has no peening of the locking lugs. The barrel to bushing fit was so tight that I had a bit of a time separating them. The inside shows the rapid and rougher machining of wartime production.
When the current owner first acquired the pistol it was in EXCELLENT condition. Unfortunately, something happened and the pistol had a bit of fine red rust develop along the exterior of slide and on the frame and trigger. That has been removed but it resulted in a bit of a finish problem you might see in the photo(s).