A gas supply system for a beverage dispensing system includes a high pressure gas cylinder including a neck having an elongated throat and a mouth at an outer end of the throat. A plug having a body and a piercable membrane is non-removably retained within the throat. The piercable membrane is recessed within the throat a substantial distance from the mouth. The cylinder also can include a shipping cap having a top and an outer wall having a circumference. At least two gas vent openings extend radially outwardly through the outer wall, and are equally spaced around the circumference of the outer wall. The gas supply system also can include a gas control valve configured to be removably mounted to the neck, and having a membrane piercing member configured to selectively pierce the membrane.