Dating Stevens
It is not possible to date Stevens as the serial numbers were allocated abitarily so that the M prefix could be allocated before the B prefix and so on. I noted on another forum that some fellow claimed to own one of the very first Favourites as he had an A prefix rifle with a two digit number - sadly he had one that was well into the production of them and indeed it was quite a late one!
I believe that the Stevens Favourite was the result of a patent taken out by Otis W Horr of Chicopee Falls in 1885, patent number 323,926. When the first Favourite came out it was known as the small sideplate model and between its introduction in 1889 and 1894 only about 1500 were made.
They were serial numbered in the same range as Stevens tip ups so that one of the very first 1894 Favourites I have here is actually numbered 40455 - it is NOT the 40455th Favourite made however but rather the 40455th Stevens made using this serial numbering system.
We can say that the three main Model designations were the Model 1889, the Model 1894 and the Model 1915. There was no Model 1910. Due to design changes there was loosely termed I believe the Model 1898, the 1902 and the 1912.
Between 1894 and 1902 I have worked out 14 different changes but the most obvious is that of 1912 when they changed from half Octagon/half Round barrels to either Octagon OR Round and then in 1915 Stamped these rifles on the tang with Model 1915.
As another contributor above said there was the standard number 17 then the number 18 and the number 19 and he has correctly stated the points that made these number designations different - that is in the sights.
There was also the number 21 - this is confusing because the number 21 Favourite was originally the bicycle rifle with a shorter barrel than the 17 but later the 21 was the 'Ladies Rifle' with a slightly different profile. The bicycle rifle had a 20 inch barrell.
The main features of the first 1894 rifles were shorter lower tang, mainspring was merely wedged against a 'capstan' and not screwed in place, the extractor came up the side of the action, the middle of the breechblock had a tightening screw, the lever was thinner where it entered the receiver, the breechblock had a slightly more rounded profile, the receiver ring had sharp edge corners (later ones were angled a little to remove the sharp edge) the receiver where the breech block rests on the face of the barrel was sharp right angled (later it had a gentle curve, the receiver beside the rear of the breech block was slightly more rounded than later, the receiver below the barrel was solid full length, the barrel shank was in two stages so it was stepped down and the interior of hte receiver profiled accordingly, the extractor entered the barrel at 7 oclock and not form below through the middle of the breech block.
Hope all that makes sense!