Beyond-armour effect is a term coined by Försvarets Fabriksverk (FFV),[1] a semi-governmental Swedish defense firm, while developing the AT4 anti-tank weapon.

From the 1980s, this phrase was used in its brochures, press releases, weapon instruction manuals and other documentation to denote the post-penetration effect of the AT4's HEAT anti-armour warhead against the interior and occupants of armoured vehicles.

[2][3] During World War II, man-portable antitank weapons using shaped charge warheads, more commonly known today as HEAT projectiles, came into widespread use with almost all armies.

The Viet Minh's main infantry antitank weapon was the old World War Two U.S. 2.36-inch bazooka, captured from Nationalist Chinese forces and supplied by Communist China.

[7] The U.S. Army also discovered that in combat, with rare exceptions, more than one hit by the M72 LAW rocket was required to disable or kill the North Vietnamese PT-76 light tank.

[8] The combat record of light anti-armour weapons was studied by the engineers at FFV working on a replacement for the Pansarskott m/68 in the late 1970s.

[9] Trumpet-shaped liners are believed to be more effective in resisting the counter-blast of reactive armour tiles, that explode and disrupt the HEAT warhead's particle stream.

[10] Tests conducted by the U.S. Army on the AT4 confirmed that the claims made by FFV regarding the AT4's devastating post-penetration effect were substantially correct.