Today we are able to take a solit shaft of steel and tap out a rifled bore.
Earlier rifles used a method whereby a piece of steel was wound around a solid rod. (Like a barber pole)
The outside would get forged smooth and the result was rifling on the inside bore.
It was fairly effective but not nearly as strong and exploding barrels were much much more common.
Looking at this video, this weapon has to be air cooled. I imagine that the shape acts like cooling fins while spinning.
I'd sure like to get a close up look at one myself.
