This is a .303 inch Rubin rimmed cartridge as acquired by Britain from Switzerland for troop trials in 1888. The case is straight sided and has a split brass collar inside the neck to hold the bullet. There is no headstamp and it has the typical Rubin very flat, square edged, primer. The addition of a rim to the, previously rimless, Rubin cartridge was because of a belief, within Britain, that rimless cases would produce feed problems in machine guns!
This cartridge has not been interfered with so it presumably still contains its 70 grain compressed blackpowder charge. Measured dimensions are:
Cartridge overall length: 78.3mm (3.08”)
Case length: 53.65mm (2.11”)
Bullet diameter: 7.9mm (0.311”)
Neck diameter: 10.1mm (0.398”)
Head diameter: 11.6mm (0.457”)
Rim diameter: 13.7mm (0.539”)
Rim thickness: 1.6mm (.063”)
Reference: .303 INCH, A History of the .303 Cartridge in the British Service. By P. Labbett & P. J. F. Mead. ISBN-0-9512922-0-X. 1988.