This is a lore summary, presenting intradiegetic or in-universe information about the subject. For game characteristics and similar data, consult the table on the right.
The .223 Remington is a commonplace rifle cartridge, originally developed for the M16 service rifle of the United States Army. Adopted with slight modifications by the military as the 5.56x45mm military round, the original .223 ammunition gained widespread popularity among the civilian population, specifically in the Colt Rangemaster, of which the round had been a standard of since 2051.[1] The common variant has a full metal jacket, offering good penetration without sacrificing damage. Its wide availability makes it a popular choice for wastelanders, due to the number of weapons that can accept the round.[2][3]
The basic variant of the .223 round offers good penetration and expansion, without excelling in either. This commercial cartridge has identical dimensions to the military round, though it is loaded with less powder, leading to lower internal pressures. Though this lowers damage, it leads to less wear on the weapon.
References
↑Vault Dweller's Survival Guide p.5-15: "A longer ranged, and more powerful, firearm. The Rangemaster is your basic, solid rifle. It uses the .223 caliber rifle round, a standard for over 110 years. The .223, combined with a 1:10” twist, gives good accuracy at range and solid knockdown capability."
↑Vault Dweller's Survival Guide p.5-17: "Rifle caliber ammunition. The FMJ stands for Full-Metal Jacket, which describes the bullet that is used in the round of ammo. A FMJ bullet is very tough, and has pretty good penetration without sacrificing good expansion. In other words, it‘s an average round."
↑Fallout Official Survival Guide p.119: ".223 Full Metal Jacket (FMJ): This is the same ammo used in the late 20th century by various military rifles, including the M-16. A good, basic, hard-hitting round."
