Welcome to the Forum.
I agree that opinions are always just that. The 1911 serious collectors have a wealth of resources, usually books by experts such as Wilson, Sapp, Harrison, Pate that detail exactly the proof marks, the parts, the manufacture dates, etc.
Something to think about is that very few 1911's from WW1 and even 1911A1's from WW 2 or Korea, or even Viet Nam were true "bring backs". If the vet was a ranking officer...then maybe, but most military weapons were just that, military weapons and remained with the Command, when the GI rotated, or went home, discharged etc.
Long guns (1903-a3, Garands, M1 Carbines), seem to be a different story and if there any old photos, bring back papers, family history records, etc. all become provenance that pretty much stays with the gun in question.
There also was a period in time where 1911's and 1911A1's could be purchased legally from DCM (now CMP) for peanuts.
Coolgunsite on the Web and the Colt Forum will assist you greatly, but for definitive value your friends gun will really need to be looked at in detail by a serious collector or expert preferably, one who already has one or more Colt 1911's so as to not be interested in purchasing.
There are also experts (find them on the Web) that will for a price, receive your friends gun and provide you a very detailed written estimate.
You may also check with a reputable Local Gun Store. There are 2 LGS in my area that charge $25.00 but you also get a very detailed, written estimate of current value, and a written estimate for insurance purposes (the values are not always the same). One owner of a LGS in my area is an expert on Lugers and was very helpful in assisting me with my 41 byf Black Widow, another Owner was (still is I think) a S&W expert and contributor to SCSW 3rd Edition, so they are out there.
Like the above posters, condition and originality are everything.
2 years ago I sold a 1911A1 Colt (WW2), all correct and matching but NRA condition wise about 85% and I got 2 hits the day it listed both for full asking price of $2,600..both hits were serious collectors, and when we met face-to-face I was not at all surprised, or offended, when we did a detailed disassembly at my place. The buyer had his reference books with him, and I had my details listed correctly so no sweat.
I also agree with family heirlooms and that value cannot really be placed on family treasures but we don't know the story or the circumstances.
As always.......research the gun in detail, and always buy the gun...not the story. Or..in your case "value" the gun, not the story unless it can be documented in some small way
Good luck in helping your friend out
