WOW! That IS a puzzle, eh?
I was gonna say it might be a Model 1895, an early version of the Model 1899... but upon checking with my sources and records, I don't believe the Model 1895 had an outside hammer either.
According to "THE" authority on Savage rifles, Doug Murray, who passed away a few years ago, even the very first Savage lever-action, rotary magazine rifle did NOT have an outside hammer. Therefore, I have no idea what you've got there since the Model 1899 did NOT have an outside hammer either.
I do know that, according to my research, Arthur W. Savage designed a rotary magazine, repeating rifle and submitted to the 1892 U.S. military trials. I can't determine whether or not that design had an outside hammer or not. Eventually, this design became the Model 1899 and, subsequently, the Model 99 Savage rifle.
However, your rifle was designated on it's barrel as being a "Model 1899" and, therefore, that should be the model is actually is unless someone has exchanged the barrel! Therefore, at this juncture, I haven't the faintest idea what you've actually got because, as far as I know... Arthur Savage's rifles
never had an outside, visible hammer on them, but the fact your rifle exists seems to contradict that premise.
Sorry I couldn't be of more help...
Strength & Honor...
Ron T.