[bwinchg]

Headstamp, RᗑL 40 F I Z
https://forum.cartridgecollectors.or...amp-list/32414

Great Britain -- "Broad Arrow" headstamp,
https://sites.google.com/site/britmi.../great-britain
R/|\L Royal Laboratory, Woolwich 1880-1954-

.50" Vickers - 7 variants,
https://sites.google.com/site/britmi...5-inch-vickers