Yes you can fella as long as they are empty, best thing to do is detach the reg or take out the burst disk and then package it up properly and then its all good I have done it plenty of times, but you have to feel comfortable in doing it so its up to you if you don't want to? They are only a hazard if under pressure as some people in the early days sent them for testing etc with air in and then they are considered hazardous cheers