ever smaller to non-existent, especially in smaller caliber shells, e.g. Panzergranate 39 with only 0.2% HE filling. Types of armor-piercing ammunition Armor-piercing – a solid shot Armor-piercing ballistic capped (APBC) Armor-piercing capped (APC) Armor-piercing capped ballistic capped (APCBC) Armor-piercing composite rigid (APCR), also known as High-Velocity Armor-Piercing (HVAP) Armor-piercing composite non-rigid (APCRNR) Armor-piercing discarding sabot (APDS) Armor-piercing fin-stabilized discarding sabot (APFSDS) Armor piercing high-explosive – a mostly solid shell with an explosive element fused to detonate after the shell has penetrated the armour protection Armor-piercing high explosive tracer (APHE-T) Semi-armor piercing high-explosive (SAPHE) Semi-armor piercing high-explosive incendiary (SAPHEI) Semi-armor piercing high-explosive incendiary tracer (SAPHEI-T) Non-kinetic-energy shells – uses chemical energy (explosion) to go through armor High-explosive anti-tank (HEAT) High-explosive squash head (HESH), also known as High-explosive Plastic (HEP) High-explosive shells Although smokeless powders were used as a propellant, they could not be used as the substance for the explosive warhead, because shock sensitivity sometimes caused detonation in the artillery barrel at the time of firing. Picric acid was the first high-explosive nitrated organic compound widely considered suitable to withstand the shock of firing in conventional artillery. In 1885, based on research of Hermann Sprengel, French chemist Eugène Turpin patented the use of pressed and cast picric acid in blasting charges and artillery shells. In 1887, the French government adopted a mixture of picric acid and guncotton under the name Melinite. In 1888, Britain started manufacturing a very similar mixture in Lydd, Kent, under the name Lyddite. Japan followed with an "improved" formula known as shimose powder. In 1889, a similar material, a mixture of ammonium cresylate with trinitrocresol, or an ammonium salt of trinitrocresol, started to be manufactured under the name ecrasite in Austria-Hungary. By 1894, Russia was manufacturing artillery shells filled with picric acid. Ammonium picrate (known as Dunnite or explosive D) was used by the United States beginning in 1906. Germany began filling artillery shells with TNT in 1902. Toluene was less readily available than phenol, and TNT is less powerful than picric acid, but the improved safety of munitions manufacturing and storage caused the replacement of picric acid by TNT for most military purposes between the World Wars. However, pure TNT was expensive to produce and most nations made some use of mixtures using cruder TNT and ammonium nitrate, some with other compounds included. These fills included Ammonal, Schneiderite and Amatol. The latter was still in wide