This thread warms my heart. I have a standard in .22 inbound after tiring of my current shot count (28). Refilling the tube every other mag isn't how I want to spend my range time... even if the gun "looks better." I won't be able to burn a tin per fill, but that's the dream!
If you already have a 300 DIN regulator, this one easily fits up between the reg and the hose: https://www.airgunsofarizona.com/regulators/huma-externally-adjustable-inline-pcp-regulator-with-integrated-fillset/ It starts to make less sense to me if you have to shell out extra $$$ adapting it...
I have just been dumping whatever ice is in my icemaker into a 5gal bucket full of water at letting her rip. I haven't felt the need to to do much more. But, like biohazardman, I was fine with it finishing up around 54C. For the heat tube idea, you might look up how to DIY an "immersion wort...
This is great information Blue, thanks or sharing! Have you had a chance to put any of the 18gr Baracudas through it? I think they spec pretty well identical to the JSBs, but seem to be a little more available, currently.