Ben,
All model 1894 Winchester rifles had their serial number stamped on the bottom of the receiver in front of the lever action and just adjacent to the bottom of the fore end. If it is not there it is because it has been buffed/sanded off. There is probably no blue left in that area or the rifle has been reblued. Either way the value has dropped dramaticaly for the collector. Like none! That doesn't meen it still won't be a good hunting rifle. If it was reblued there probably are not any nice sharp edges on the receiver as they will appear more rounded. See the photo for correct serial number location. And I would love to see a picture of the same area on your rifle.
Good luck
2bit