Sometime, I think20 or 30 years ago, someone (95% sure Layne Simpson) did an article in Handloader or Rifle about water cooled varmint rifles. IIRC, it seemed like a God-awful amount of money at the time.
I thought it might have been "Guns" Magazine, but I sure wouldn't want to fight over it. I also wouldn't want to bet on my memory from back then. You could very well be right.