I have been considering the purchase of a Co2 speargun (MACO2) for over a year now, and I ordered one yesterday. Cant wait for it to get here. It is the "Grande" model with a 10mm spear. Anyone have experience with a Co2 or air powered gun? I plan on using air for the propellant, and have ordered an apparatus to fill the smaller gun bottle from a scuba tank. Is there any difference in the performance between air or Co2? The dealer said that the air was less likely to damage the o rings, but did not say anything about overall performance.