(Phoshor mit Stahlkern-Tropen) PmK-Tropical, pointed bullet with steel core, incendiary (API) Tropical. Black primer annulus and neck sealant. White phosphorous (removed) incendiary that lies behind steel core, with lead bottom. Headstamps: ayv/s*/5/42, amp/s*/5/42. One had square powder, the other stick. Developed for German Luftwaffe (Air Force) as a high velocity machine gun ammunition. Thanks for looking, wolfgang.