A very rare chambering indeed.......apparently not too popular and faded into obscurity fairly early on.
Possibly due to the onset of WWII then after the war the hunting bans in India?

The only load data I have found is from "Cartridges of the World" as well as an article in the 1972 6th edition "Handloaders Digest" by Ken Waters.
Per Cartridges of the World the original .242 Vickers loading is said to have been 40.5 grains of "Nitro Cellulose" for 2800'/sec with a 100 grain bullet.

Cartridges of the World:
39 grains of 4350
34 Grains of 4895
both for about 2800'/sec

Ken Waters data:
42 grains of (IMR?) 4350
48 grains of H4831
no velocities mentioned; Waters' loads in his "Pet Loads" tended to be pretty hot.

The .242 Vickers cartridge is similar to and only slightly larger than the 6mm/.244 Remington so starting loads for the 6mm/244 Rem look like a decent guideline.

Right now Cogswell & Harrison are stumped because of the 4 digit serial number, they are still checking.........maybe a Vickers made and numbered rifle marked and retailed by Cogswell and Harrison? The barrel is marked "Cogswell & Harrison, Ltd" which indicates that the rifle is from some time after the 1932 liquidation and reorganization of Cogswell and Harrison.

- Mike