Blanks in SMG
From Halopedia, the Halo wiki
Template:Ratings When wielding an SMG, it is possible to fire open blanks. One of the simplest and easiest ways to do this is to melee as you are firing the SMG and when the gun returns to its firing position, the gunfire sound can be resonated and heard, but no bullets are used. This can be used to scare off your opponents in Capture the Flag and Oddball.
A second way is to change to monitor mode in forge while firing an SMG. The sound can be heard from proximity, and will not stop until you return to player mode.
