Here's what was issued to Indian Police:
In 1883, Remington supplied approximately 1300 nickle-plated revolvers to the Indian Police.
Nothing is indicated in the Contract about particular markings, if any - but they were trying to cash in on Colt's Government Contracts and referred to the revolver as the "Model Furnished Interior Department for Indian Police".
Often - Remington-Keene rifles are seen - stamped "U.S.I.D", as are Whitney-Kennedys and Winchesters.
According to "Flayderman's Guide to Antique American Firearms" - the caliber is quoted:
"Caliber .45 Government listed in early Remington catalogs (actually .45 Long Colt), but specimens scarce and would be worth premium; buyer should exercise caution on this latter caliber."
According to Wilson's "Price Guide to Gun Collecting" - the quote reads:
"Model 1875 Army Revolver, .44 centerfire, later in .44-40 and .45 Long Colt, 7 1/2", 5 3/4" Barrels bring Premium with web below Barrel."
Government purchase figures for U.S.I.D. are as indicated.
No mention of the Model 1890 - since the Government only bought the Model 1875.
There's more - but these are readily available references.
Now as to the nickel-plated Colts - it's been pretty much disproved that they were for the Indian Scouts - but rather, they were private-purchase for Officers.
Vaya,
Scouts Out!