I got a good gun you can make it's called......."SAW" (Squad automatic weapon)
Specifications
Weight 7.5 kg (17 lb) empty,
10 kg (22 lb) loaded
Length 1,041 mm (41 in)
Barrel length 521 mm (21 in)
Cartridge 5.56x45mm NATO
Action Gas-operated, open bolt
Rate of fire 750–1,000 rounds/minute
Muzzle velocity 915 m/s (3,002 ft/s)
Effective range 1,000 m (1,094 yd)
Feed system M27 linked belt, STANAG magazine