From the Blazer Owner's manual (
Blazer owners manual - Paintball Palmer
An air leak (or venting) at the hole near the regulator adjusting screw at the front of the gun, indicates an over-pressured state in the regulator that has caused the "over-pressure" relief valve to activate and vent the system safely. Refer to Pressure Regulator Adjustments section and reduce the regulator's output pressure.