This Sportline M4 Armalite S.I.R value for money is a good option
With Armalite full license and marks and super easy and quick access to the battery
Features:
Adjustable hop up
Length: 775-858mm
Barrel length: 392mm
Weight: 2450g
Muzzle velocity: 367FPS
Power:1.3joules
Mag capacity: 350rds