This is from the book: Mit dem Drilling durch Vorderasien (1967).
The authors write: That the Shikaris had rifles for bullets (on an other side an 7 mm Kaliber), they are good shoots, but then they hunt (or guide) tigers, they use their shootguns. Because they think they are more praktical - with the rough shoot - in the thick bush.
This makes a lot of sense based on my own experiences as well. The rifles were likely made by Ishapore Arms Factory in .315 bore . This was built on a Lee Enfield type mechanism with a removable magazine holding five cartridges . Each cartridge had a blunt , soft head 244 grain weight bullet. You are European , and l think you will understand the cartridge better as an Indian version of the 8 millimeter by mannlicher cartridge .