Umarex Legends M1A1 Full Auto .177 Caliber BB Magazine 30 Rounds Black. 177 caliber airgun. This magazine holds 30 .177 caliber steel BBs and two 12 gram CO2 cartridges just like the one that came with the M1A1. A new Allen key for the CO2 screw also comes with the magazine. Specifications for Umarex Legends M1A1 Full Auto .177 Caliber 30 Round BB Magazine: Manufacturer: Umarex Color: Black Fabric/Material: Steel Magazine Capacity: 30 Round Caliber: .177 Pellet Gun Make: Umarex Gun Model: Umarex Legends M1A1 Thompson Full Auto BB Gun Features of Umarex Legends M1A1 Full Auto .177 Caliber 30 Round BB Magazine Fits Legends M1A1 Full Auto BB Gun Holds (30) .177 Caliber Steel BBs 2 x 12g CO2 Housed in the Magazine Package Contents: Umarex Legends M1A1 Full Auto .177 Caliber 30 Round BB Magazine CO2 Screw Key What firearm models does the manufacturer say Umarex Legends M1A1 Full Auto .177 Caliber 30 Round BB Magazine is compatible with? The manufacturer says that Umarex Legends M1A1 Full Auto .177 Caliber 30 Round BB Magazine is compatible with Umarex Legends M1A1 Thompson Full Auto BB GunUmarex 2251821: Legends M1A1 Full Auto .177 Caliber BB Magazine 30 Rounds Black