According to famed "old shooter" Phil Sharpe, in his classic reloading book, he gives "designed by Win for use in their 1894", (which is commonly repeated)...."The cartridge was originally designed for 30 grains of black powder, but the powder and metal jacketed soft point bullets did not get along very well, and accordingly early loads were altered to handle smokeless powders" end quote.
Since the last designation in most of the rounds of the day, did signify the amount of black used, I would buy that the last number came from the grains of black intended to be used. They did have smokeless that imitated Black pressure issues, all are obsolete far as I know.
Generally after the transition, the grains of powder used in the name went away. It was still used of course, but had zip to do with the actual amount of smokeless used.
Sharpe says about the 25 35, "one of the Win series born around the turn of the century" then later on the 25 36 Marlin..."this cart. designed by William Lowe, as the 25 37, Marlin adopted it around 1897 but chose to call it the 25 36 Win followed shortly there after with the 25 35 WCF"
Sharpe was not a phony, and was one of the leading gun experimenters of the day. He certainly does not get the creds that a few of the others do, but his work was well tested, and he was not one to take credit for things developed elsewhere.
All the varying dates, leads me to believe that "who was first" depends on who told the story, and how large the tellers ego was.
But its like a lot of gun developments, to believe that Win totally had an original idea on the 30 30, and Marlin was out in the dark, is a little naive. Especially with the info offered by Sharpe on the 25 36 trivia.
I suspect both outfits were burning mid night oil, to "be first".
