WW1 cartridge quiz

[browningautorifle]

This is about what I can find, nothing on the bullet weight though. .303 inch Rimless - British Military Small Arms Ammo

Don't know if this is the exact same cartridge... .303” Enfield Rimless Experimental Cartridge Tested between 1920 and 1927. Five thousand rounds were produced, loaded with 48.7 grains of nitrocellulose power and either a 174-grain or 200-grain projectile. Case length was 2.21” and bullet diameter was a small .309”.