Hello,  I inherited this rifle when my grandfather passed away four years ago and I am just now picking it up from my family in NY and trying to get it back to CO.   It is the first rifle I've ever owned, and the history of the rifle is fascinating.   The action and barrel seem to be in good shape and I hope that it is in useable condition.   I'll get it looked at by a gunsmith back home when I have the time.

The Redfield apature sight, front sight, sling and swivels are not original.  There does not appear to be a cartouche anywhere on the stock so I'm assuming it was replaced?

Any info about this rifle would be appreciated. 

Thanks for the info.   I figured it was a bit of a mutt after looking through the 1898 manual and seeing the mismatched sight and action. 

It's not necessarily a mismatched action and rear sight. An 1898 rifle could correctly have an 1898 rear sight, a 1901 rear sight or a 1902 rear sight, the first and the last are very much alike. Probably if the rear sight seems correctly mounted and its remaining finish is similar to the barrel and action, they are all original. I have a feeling that your 100K series serial number is probably indicative of a 1901 manufacture date too, which would support the idea that all the metal is original. Maybe one of the collector experts can verify that.