So I have an S&T M320 grenade launcher I got some time back and I use it as a standalone side arm (kinda like in battlefield) with one of various AEG rifles and carbines I own depending on the scenario on a sling along with bb shower grenades. Although great in cqb room clearing, I decided it would be much more effective (and much cooler) to launch single projectiles longer distances for use taking out bunkers, vehicles, and groups of people. I want the grenades to fit in a short m203 grenade pouch, so carrying foam rockets is out of the picture for me. So I decided maybe buying the G&P rubber cap launching ones. It gives a decently ranged single, cheap, easily replaced projectile, and it will surely fit in my pouches completely. My question however, is what type of gas will offer me the best range on these single projectiles without damaging the grenade significantly? Propane, Green Gas, or CO2?