5 0 0 mm ▁bar rel . ▁ ▁: ▁G endar mer ie ▁: ▁Limited ▁numbers ▁to ▁Belg ium ▁Police ▁ ▁Non - state ▁actors ▁▁ ▁I zz ▁ad - D in ▁al - Q ass am ▁Brig ades : ▁Most ▁likely ▁of ▁Lib yan ▁origin . ▁ ▁M x 4 ▁Storm ▁ ▁The ▁Ber etta ▁M x 4 ▁Storm ▁is ▁the ▁military ▁version ▁of ▁the ▁C x 4 ▁Storm ▁p istol - cal iber ▁car bine . ▁It ▁has ▁a ▁bar rel ▁length ▁of ▁ 1 2 ▁inches , ▁and ▁is ▁capable ▁of ▁automatic ▁fire . ▁The ▁M x 4 ▁can ▁use ▁p istol ▁mag az ines , ▁or ▁its ▁own ▁ 3 0 - round ▁magazine . ▁There ▁is ▁an ▁access ory ▁rail ▁on ▁the ▁top ▁of ▁the ▁M x 4 ▁for ▁mount ing ▁scop es , ▁las er ▁aim ing ▁devices ▁or ▁flash light s . ▁There ▁is ▁another ▁rail ▁under ne ath , ▁forward ▁of ▁the ▁trigger , ▁for ▁mount ing ▁vertical ▁for eg ri ps , ▁las er ▁aim ing ▁devices ▁or ▁flash light s . ▁ ▁Users ▁▁ ▁: ▁In ▁service ▁at ▁least ▁since ▁ 2 0 1 6 ▁ ▁: ▁On ▁February ▁ 1 4 , ▁ 2 0 1 1 ▁an ▁order ▁for ▁ 3 4 , 3 7 7 ▁car b ines ▁was ▁placed ▁by ▁B SF ▁( Border ▁Security ▁Force ) ▁personnel . ▁ ▁The ▁guns ▁were ▁delivered ▁in ▁two ▁batch es : ▁The ▁first ▁batch ▁of ▁ 1 7 , 0 0