Jim Riggs wrote a book called Blue Mountain Buckskin. The method used in this book is called dry scrape. Basically string a hide in a frame and let it dry, scrape the hair off.I have also strung a hide and let it freeze in the frame and then fleshed it and scraped the hair off.
The Mcphersons method is also
dry scrape
I prefer the dry scrape vrs wet scrape. Wet scrape is soaked in a bucket of bucking solution (ash water) i like the dry scrape because I can walk away from it. A hide in bucking solution cant be left to long but if time is there,thats ok too. I have also wet scraped fresh hides, no soaking.
There are as couple books from Fur Fish.Game. they sell historical books and they have a couple on tanning.
I have also tanned furs using a battery acid mix. Also have used a paste using alum and oatmeal. Those books have that info.