The first tanks, beginning with the British Mark I launched against the German trenches in World War I, were nearly impregnable to ordinary rifle fire.
Both types had their specific advantages and disadvantages: for example, the K bullet was more expensive to produce and therefore was generally only issued to snipers and other advanced marksmen who could use it more effectively; the ordinary infantryman had to make do with reversed bullets, which were far less effective and had to be used in closer proximity to the target.
Nevertheless, it gave the infantry a chance to stop a tank in an emergency, or at least injure or kill some of the crew if a bullet penetrated.
The Mauser 1918 T-Gewehr large-calibre (13.2 mm) rifle was capable of penetrating the armour of the newer generations of tanks and allowed a chance at stopping them.
When word of the German anti-tank shell spread, there was some debate as to whether it should be copied and used as a base for the new machine gun cartridge.
However, after some analysis the German ammunition was ruled out, as its performance was inferior to the modified Springfield .30-06 round and was semi-rimmed, making it difficult to feed into an automatic weapon.
At the start of World War II, only some European nations had an anti-tank rifle based on a high-velocity, large-calibre round.
In later years of the war, as armour became thicker on newer tanks, the effectiveness of a man-portable rifle lessened.
This was particularly true in Malaya, where the light Japanese tanks specially configured for jungle conflict rode roughshod over British forces supplied with the Boys anti-tank rifle.
To these were added rocket launchers such as the bazooka, recoilless rifles such as the Panzerfaust, and rocket-propelled grenades — some anti-armour successes were achieved with heavy-calibre autocannon by the Luftwaffe, especially with the Bordkanone BK 3,7 autocannon, mounted in twin gun pods against Soviet armour on the Eastern Front.
[4] They are also useful in disabling or even destroying lesser armoured rear units and support vehicles, helicopters, low-flying UAVs and personnel.