I had to look that up. 12.17×44mm R (rimmed) is the civilian centerfire version of the Norwegian/Swedish 12.17×42mm / 12.17×44mm RF (rimfire) for the Remington 1867 rolling block. My thanks for calling this bit of history to my attention.
Wikipedia:
Centerfire 12.17×44mmR cases are available, but a more cost-effective way to acquire cases is to cut .50 Alaskan cases down to 44mm total length.[7]
7. Oyvind Flatnes, "From Musket to Metallic Cartridge: A Practical History of Black Powder Firearms", Crowood Press, 2013, pp. 134–138.