I've done it once or twice. Only ruined one rifle. Not just ruined it but went the whole hog and destroyed it............ We always left a bolt and bolt head in the action for some reason unknown to man. I did exactly that but didn't notice that the bolt head still had the extractor installed. Barrel just started to turn and tightened up. Tried to overcome the 'tight-spot' by unscrewing it a bit more ....., and more...... and more until it went further and totally defeated me. Nothing was going to save the barrel, barrel threads or the body or the extractor and the bolt was never ever coming out of that body. You can have all the right kit but just a slight lack of concentration and you're knackered!