The wad slug is loaded using a standard shotshell wad, which acts like a sabot. Firing a smaller-sized projectile wrapped in a sabot raises the muzzle velocity of the projectile. A modern variant between the Foster slug and the sabot slug is the wad slug. Shotgun slugs often use a cast plastic sabot similar to the spindle sabot. The -long penetrator together with its sabot weighs . Tungsten carbide ammunition is now generally of the sabot type. Armour-piercing discarding sabot (APDS) was initially the main design of the kinetic energy (KE) penetrator. Armour-piercing fin-stabilized discarding sabot tracer or APFSDS-T rounds. It was used to evaluate improvements to the gun's performance using discarding sabot ammunition. Modern KEP munitions are typically of the armour-piercing fin-stabilized discarding sabot (APFSDS) type. The M829 is an American armor-piercing, fin-stabilized, discarding sabot (APFSDS) tank round. An important armor-piercing development was the armor-piercing discarding sabot (APDS). For example, a long line of armor-piercing discarding sabot (APDS) rounds was developed by Rheinmetall. In January 1962 the first test shot was carried out, firing an empty sabot. This variant is unofficially referred to by Abrams tank crews as the "super sabot".