Green Gas

The propane base gives consistent, moderate pressure at typical outdoor temperatures, and the mixed-in silicone oil lubricates a magazine's internal seals and valve every time it's filled, which is part of why gas magazines last a long time with basic care.

Pressure drops sharply as temperature falls, which is the main practical limit of green gas: below roughly 5–10°C output pressure and shot count both suffer, sometimes badly enough to short-stroke a blowback action. Cold-weather shooters either switch to CO2, which holds pressure far better, or keep magazines warm between uses.

Shaking the bottle gently before filling helps redistribute the silicone oil that can settle out over time, giving a more even mix into the magazine rather than a fill that's mostly propane followed by mostly oil.