have you seen the fail thread?
Pro tip - Tokyo Marui gas blowback pistols DO NOT need metal slides to run propane. Trust me I own one.
Follow up - I don't suggest metal propane adapters. The one I had broke my mags in < 3 weeks. Plastic adapters have many more pros than metal ones. Don't believe me? HolyHandGrenade has the most experience on the forum (that I've heard of) with any adapters.