Compressed air and nitrogen are functionally identical. Both are pure because compressed air is filtered to be breathable through scuba gear; the compressors used in paintball are based on, if not the same as, the ones used by dive shops. Jynx is exactly right on the issue of the Titanium barrel, which hopefully by now should be remedied if the people I talked to from Chicago have advised DYE to change to a titanium-nickel alloy, which a 10th grade knowledge of chemistry should have told them to do in the first place.