Is there any distinguishing a WWI-1986 M1911a1 between Army and USMC ownership?
Yes, but only for the first 7 years of shipments, circa 1912 to 1918. As noted in books by Clawson, Poyer, etc, the USMC received small shipments of known serials ranges of Colt 911 pistols, which are:
1912: 3501-3800 (300 total)
1913: 36401-37650 (1250 total)
1914: 83901-84400 (500 total)
1915: None
1916: 151187-151986 (800 total)
1917: 209587- 210386 (800 total)
1917: 215387-216186 (800 total)
1918: 216987-217386 (400 total, and as noted by Poyer "Last direct shipment to USMC").
Total: 4850 Colt 1911s shipped directly to the USMC
All of the slides had the standard marking: "MODEL OF 1911 US ARMY" - so the serial #s are only way you can you tell if these pre-WWI and WWI era pistols went to the USMC. After 1918 the pistols were shipped to the US Army, US Navy or in WWII to "General Stores" - none were documented as going directly to the USMC
So, that's less than 5k pistols in the early years, and given the attrition rate of WWI and WWII, Korea and Vietnam, they are very rare. Most have probably landed in advanced collections over the past few decades, and presumably sell for a large premium over a similar era 1911 (I think I saw a worn specimen at a gunshow many years ago for $7500. The tag said it was in the USMC serial range, but too much $$ for me so I didn't study it).
FWIW, there is an old 2112 in NC who is building clones of the USMC MEUSOC pistols, while not historic, but they can be used and enjoyed - unlike a 100 year old 1911 with a lot of collector value and an ever-increasing price tag...
https://kcskustomcreations.com/meu-s...nd-price-list/
I don't collect 1911s, but I did gather up the right parts and had two PWS-built 1911s made by 2112s. (One is an early MEUSOC with a 1943 Colt frame as configured by USMC/RTE in the late 1980s, and other is the final variant of the USMC M45 with the Springfield Operator slide as made by PWS in 2012-2013). I have not shot either one as I consider them collector's items and I have other 1911s for shooting. (see attached)