GBB magazines for the M4, MP5, MP7 and SVD.
GBB magazines like for example for the HK 416 can only be used in GBB rifles and working as the name says on Gas.
GBB Magazines can be compared to realcap magazines as they can generally hold the same number of bb's as the real steel magazines hold bullets. This means that if you want to get through a game a bit well, you need to carry a number of magazines with you so you have enough bb's and can change quickly when the mag gets empty.
