The issue is a nature of the regular greas gun and regualr nozzle, it is caused by the kept pressure in the hose/nozzle which will make the coupler clamp the zerk fitting tightly still, as long as there is no kept pressure in the hose/coupler, it will be easy for the user to remove the hose/nozzle from zerk fitting.

Brand: Bravex
Cartridge Capacity: 14oz.
color: Silver
Country/Region of Manufacture: China
Maximum Pressure (PSI): 6,000 PSI
Modified Item: No
Non-Domestic Product: Yes
Power Source: Manual
Type: Grease Gun
Warranty: 2 Year