G&g m4 sd full metal electric gun

new full metal model available
8mm gearbox with 1j spring and steel gears
reinforced piston and hi toruqe motor
aluminum rail system and metal barrel with silencer
retractable crane stock with battery housing for separate battery 
450rd magazine included
Length: 790/880mm
Weight: 3480g

Technical data
-reinforced 8mm gear box with ball bearing
-1 joule power tempered spring with seal nozzle
-reinforced steel gears
-reinforced piston with polyamide piston head
-hi torque motor long axle
-nylon hop chamber with 275 mm precision inner barrel