S&T M4 KEYMOD 13" GBB BK

The S&T M4 Slant Cut Keymod 13" Gas Blowback is exactly like that 9" except it's longer in length.
It uses the WA gas blowback system this ensures reliable performance even with aftermarket parts. The rifle has an injection moulded polymer receiver allowing it to be lightweight.
The SOPMOD stock is adjustable.
The flat-top receiver features a 20mm rail to mount optics. The 20mm railed Keymod compatible handguard has Keymod mounting points on the 3, 6 and 9 O'Clock positions. Uses green gas. This rifle is quite similar to the M4 Slim Cut Keymod 9". 
 
Features 
WA Gas Blowback System 
Injection moulded polymer receiver 
The improved gas efficiency, reliable feeding and firing in full auto
Adjustable SOPMOD type stock
Flat top receiver is ideal for mounting optics or other 20mm accessories
20mm railed Keymod compatible handguard with Keymod mounting points on the 3 O'Clock, 6 O'Clock, and 9 O'Clock positions
 
Main Materials 
Metal 
Polymer
 
Package Includes 
S&T M4 Slant Cut Keymod 13" Gas Blowback 
Manual 
50rd Magazine