Definitely a replacement barrel. If you pull the magazine tube and forend stock off, you will find a 2-digit year number stamped on the bottom for the barrel in the concave groove near the receiver frame, which will tell you what year the barrel was made, and the earliest possible year that the rifle was rebarreled.
Yes, Winchester (on special order) did equip the Model 1894 with the style of butt plate on your rifle.
WACA 6571L, Historian & Board of Director Member
March 21, 2016