How to Build the SBR M4 in Gray Zone Warfare To build the Short-Barrel Rifle M4 in Gray Zone Warfare, you must first unlock Gunny level 2, which will unlock additional weapon attachments.

but few are as popular as the M4 assault rifle. Endlessly customizable, the US-made M4 is a highly capable AR, suitable for short, medium, and long-range combat. In the past few seasons ...