I was fortunate to pick up some Kynoch original 375 X 2½ in sealed boxes date coded 1938. In the interests of research I pulled one cartridge and it contained exactly 40 grains of stick cordite in a balloon head case. The bullet had a thin glazed card wad underneath it. The bullet weighs 270 grains and is stab crimped into the case very close to its base. Amazingly the bullet has the letter “K” embossed on its base. Heaven alone knows why they did that but it does look nice. As I had 34 rounds of this I shot five rounds over my chronograph to see what they do. They averaged 1958 fps and were very consistent. They are undoubtedly corrosively primed so I had to scrub the gun out well afterwards. A reproduction of an old ICI Sporting Ammunition Catalogue I have gives a muzzle velocity of 2100 fps from a 25” barrel but I can only report the results I got.