A couple of weeks back I came across a large calibre round on Huddersfield Market that I did not immediately recognise. As it was only £3 I bought it speculatively and took it home with me. Comparing it with my Boys AT round (middle) and a .50 cal drill round (lower) it was clearly slightly ‘chunkier’:Some help from other collectors has now helped me to identify the round as being a 15mm Besa round:The 15mm Besa machine gun was an enlarged version of the Czechoslovakian ZB53 machine gun and was introduced to replace the obsolescent .5 Vickers machine gun. The 15mm Besa was a long and heavy gun, weighing over 125lbs and being more than 6 feet long:It was therefore used mostly to arm wheeled armoured scout cars, such as the Humber:The round has a 1160 grain bullet fired from a 15x104mm cartridge:I believe that this is a ball round, and it has a boattailed shape, the round being filled with a lead/antimony mixture. The rounds were fired from 25 round metal belts, that reduced the rate of fire. However the machine gun was normally fired in single shots which were far more accurate than automatic fire. The round has a rimless case, with markings on the base, sadly I cannot read any markings in this case:This round was very short lived, being introduced in October 1939 as the “Cartridge S.A. Ball 15mm Mk 1z” and being declared obsolete in August 1941. The round was used primarily for training. The 15mm Besa itself would not last much longer, being declared obsolete in 1949, over 3,200 machine guns having been produced by that point. I have never come across one of these rounds before, I really like these large calibre rounds so it’s a great addition to my small but growing selection of ordnance.