Please help me ID my gun!

[NewColtGuy]

Last year I purchased a Colt 1911, by the serial# 341990 it was manufactured in 1918. The markings on it are what is most confusing to me. On the left rear of the slide is the Colt stamp. Centered on the left are the 4 patent dates. Also on the left, but on the reciever, behind the trigger guard, and below the magazine release is the Springfield armory eagle head S5 proof stamp. On the right of the reciever is the serial#. Stamped on the right side of the slide is Colt Model 1911 US Army, and also "calibre .45 automatic". There is no stamp anywhere on the weapon that says property of US Government, etc. It also has the 2 tone WWI magazine, but I am unsure how to identify that further. Magazine does not have a lanyard loop. I am very confused about the "calibre 45 automatic" marking, and the lack of government property stamp. Of all the guns I have looked at online, none match mine. The gun also doesn't have any arsenal rebuild markings that I am aware of. If anyone could provide me with any information regarding this weapon, I would greatly appreciate it.

[stans]

The slide sounds like a Colt commercial/military 1918 slide. Not sure about the receiver, it may have at one time had the United States Property marking, but was ground off or welded and remachined.

[exitwounds]

The slide sounds like a Colt Commercial/Military Slide, circa May/June of 1918.
The marking should be MODEL OF 1911. U.S. ARMY, forward that COLT AUTOMATIC over CALIBRE 45. The UNITED STATES PROPERTY stamp would have been on the left side frame forward the slide stop, it was probably ground off since it has the eagle head S5 which was used on Colt 1911 pistols from May 1918 through Apr 1919.

[NewColtGuy]

You are absolutely correct about the slide stampings...I made the post while at work, and obviously was unable to have the gun in front of me at the time. Why would the property stamp be ground off on guns with an S5 marking? Was that something that was done to the gun when it was made, or was the stamp and grinding done when it was returned to the armory after issue?

Thank you for your help!

[PZ93C]

US Property markings would have been ground after it was in civilian hands. Maybe someone, after the war, brought that back with them. There was a fear of being caught with a US Property firearm and they had it ground off the weapon.

Once upon a time, US Property had some meaning.

Brian