K bullet

Also: Patrone SmK (Spitzgeschoss mit Kern) 8×57mm IS

The standard 8×57mm IS caliber 'K Bullet' as designed before the Allied Invasion. Note the tool-steel core protruding from the rear of the bullet to form a boat tail.

A tracer variation of the 'K bullet', "L'spur (gelb)" or 'Tracer (yellow)'.

The K bullet is a 8×57mm IS armor-piercing bullet which has a tool steel core and which was designed to be fired from a standard Mauser rifle. It was used by the German infantry against the first British tanks in World War I. The K bullet had a probability of approximately one-third to penetrate armor 12–13 mm thick up to a distance of 100 meters.

The K round was in use by the battle of Messines Ridge in June 1917 which was the first use by the British of the Mark IV tank which had more armour and was resistant.

Variants

The Germans made several versions of the K bullet during World War I and World War II, including:

Designation	Full Name	Description
S.m.K.H.	Spitzgeschoss mit Kern, Hart	Replaced the tool steel core with a tungsten carbide core.
S.m.K. L'spur	Spitzgeschoss mit Kern, Leuchtspur	Has a shorter steel core, and includes a tracer composition. May include color designation such as (gelb) which means "yellow".
S.m.K. Ub.m.Zerl.	Spitzgeschoss mit Kern Übungsmunition mit Zerleger	A very rare practice bullet which self destructs after a certain distance.