Brand new all-metal semi automatic FN HERSTAL M4A CQB Co2 BB air rifle by CYBERGUN comes with R.I.S. quad tactical Picatinny rail sytem and full metal carry handle. The fully detachable magazine comprises both an 18 BBs feeding tube and a Co2 bulb. This M4 is the REAL dimentions of 5.56mm M4 CQB (Barrel length 285mm / 15"). It has all the correct markings of a real rifle including a 3-position fire selector, 5.56mm calibre and serial number. The Co2 M4 CQB imitates the high quality alluminium-made upper and lower receivers of a real weapon, with a steel gas tube and all moving parts including a charging handle, forward assist button and removable carry handle. What's more, we can increase the power of the magazine by about 15% - 20% by re-machining its main air valve to allow more air preasure into the barrel as an option. Spare magazines with increased energy of appx 4 Joules (450 fps) are available