.223 round

The .223 round is a type of ammunition in Fallout, Fallout 2 and Fallout: New Vegas. Due to the specific dimensions of the .223 round, it is used as an offshoot of normal 5.56mm ammunition and will fit in any weapon chambered for 5.56mm.

Background
The .223 round is a cartridge with almost the same external dimensions as the 5.56mm, but while the external case dimensions are very similar, the .223 and 5.56mm differ in both maximum pressure and chambering.

.223 round


Standard .223 caliber ammunition has a lower internal pressure than its military-standard cousin, and as such deals less damage to the target. However, this also decreases the stress put on the weapon, resulting in better weapon durability.

.223 FMJ


Full metal jacket rounds are exceptionally accurate, common, and cheap. They lack any sort of damage multiplier, but are able to punch right through lighter armor.