5.56×21mm PINDAD
The 5.56×21mm PINDAD was a personal defence weapon round previously developed in Indonesia. The round is based on the 5.56×45mm NATO cartridge, being a cut down version of it. It's sometimes known as 5.56×23mm. Development
The 5.56×21mm round is said to have the same firepower from a .40 S&W or 10mm round. Platforms using this cartridge
 Pindad PS-01

See also
 .22 TCM

References

Pistol and rifle cartridges
5.56 mm firearms