Re: Is This a Remington Revolver ?
OK, fair enough. To answer your one question, I have no idea who made that gun or when or where. I do know it does not date to the Civil War era.
Those dimples are the marks of ejector pins, associated with injection molding (casting), a technique NOT used in the Civil War era. If you want, you can look up the date injection molding was first used but I am pretty sure it was well into the 20th Century. In other words, your gun cannot have been made in the Civil War era, and that makes any other analysis or comparisons pointless.
FWIW, casting in the mid-19th century was almost always sand casting; that was not commonly used for quality guns, which were milled from iron blocks. Colt frames were made by heating a block of iron (called a "shoe"), bending it at a right angle, facing off the bottom as a reference point and machining away anything that didn't look like a revolver frame.
You can buy a copy of Flayderman's. Even though the pictures are fairly small, they are good enough to make the differences clear and that your gun is not any of the Remington revolvers of that era. But, that would be pointless in the face of those ejector pin marks and what appears to be a filed off sprue mark.
The real origin of the gun and the anomalies? I don't know. Repros of Civil War era revolvers were certainly being made by 1958, as the Civil War Centennial approached, and your father may well have had one; the gun of your grandfather's that you remember may have been another one; someone in your family might have bought a repro and it was beat up over the years; someone may have even sold the old gun and substituted a cheap repro. Again, I simply don't know and have no way of knowing.
Those questions won't keep you from putting the gun in the holster and selling the combination as "percussion revolver in old holster" or something like that, without making any claims as to the identity or age of the gun (the holster is definitely old). The buyer can believe anything he wants.