Great photo! The reason for the M4 is the Uzzi is a 9MM pistol round which is fine for CQB (Close Quarter Combat). The M4 uses 223 rifle round which has a much greater velosity and range. The 11 in barrel and collapsable stock makes this weapon a perfect mix between CQB and medium range weapon. Zero'd at 50 yards it is poit of aim point of impact from basically 25 yrds at 100 yds. Much faster round and more energy than the 9MM.