Specna Arms CORE Series M4 SBR 6mm
36 - 30.96 lbs Lightweight polymer construction Metal flash hider, barrel assembly, sling swivels, and charging handle Full auto and semi-automatic Hop-up: Yes Quick change spring system Speed: 380 FPS with installed spring (310 FPS with included spring).7” (adjustable) Weight: 4.Specna Arms CORE Series M4 SBR Length: 27.