Airsoft BB's, in Simple Terms

Weights of bb's:

.12g - Used in most Springers, LPEG's and mini-electrics FPS* - under 300
.20g - Used in lower powered AEG's, lower powered Sniper Rifles, lower powered MPEG's, higher-end Springers FPS* - between 260 and 330
.23g - Used in AEG's, Sniper Rifles, MPEG's, high-end Springers FPS* - between 260 and 375
.25g - Used in AEG's, some upgraded guns, Sniper Rifles FPS* - between 275 and 410
.28g bb's or heavier - Used in heavily upgraded guns, high-end Sniper Rifles FPS* - 350 or above


Brands of bb's:

High grade bb's, These bb's are good enough to use in AEG's, Gas Guns, or any other gun without jamming:

KSC
Excel
Tokyo Marui
Airsoft Elite (AE)
Systema
AIM
SRC
Matrix
Stealth
Maruzen

Mid-grade bb's, used in lower priced guns.
**Note with some mid-grade bb's silicon oil can be added to provide a slicker surface and make them less prone to cause a jam.**

Crosman
KWC
Inertia
Toy-Tec
Toy-Jet
Infinity
Viper
Cybergun "Special Selection"

Low Grade bb's, these bb's aren't recommended for anything. They can only be reasonably used with a low-end springer or a mini electric.

Most .12g bb's that are sold at no-airsoft stores.
Cybergun
Stinger



*- FPS is with said bb's