yeah that'ss the style I've seen.... (external, water, short scribe)

The only way to light an internal torch would be an electronic ignition, or to flood the tube with the gas/air mixture, ignite one end, and let it propagate to the torch tips... would make one hell of a pop!

I've always wondered is a hot wire cutter would work on heavy wall tube.... I have the parts to make one, just haven't done it (yet).