Hey Steg,
Stay far away from hot water, unless you like a flash rusted bore. Room temp is best.
Unless you are getting corrosion in your bore, I don't see how it can be getting tighter. Rougher may feel like tighter.
Here is a thought for you. Not all cleaners will remove all lubes or firing byproducts. Makes sense once you think about it. If you cook grease onto a pan, does plain water remove it?
I have now switched to Mr Flintlock Lube for both lube and for final cleaning. I changed on the sage advice of Bill Knight.
I had been cleaning my gun down to what I thought was bare metal each time I shot. No grunge or rust, but fairly often I saw what looked like a fine pencil line on a cleaning patch. On Bill's advice, I tried Mr Flintlock and the patches came out BLACK for a long cleaning session. The black was graphite, and the lukewarm water I was using did not cut the graphite. The bore seemed clean, until I got something that actually cut into the graphite.
For initial cleaning (filling the bore for a soak) I am using cheap windshield washer fluid. It seems to work better than plain water. Once the patches are pretty clear, I run down a dry patch or two, and then start with the Mr Flintlock. That removes the graphite cooked onto the bore.
I don't think that the Mr Flintlock is as slippery as some lubes, but I know for sure that Mr Flintlock on a cleaning patch will remove the Mr Flintlock residue from firing. And graphite.
I'll say again, when you change lubes and fire rounds, know what it takes to get that cooked lube back out of the bore. That is why I quit using Teflon that I had been taught by a target shooter. I researched, and could not find any solvent that can touch Teflon. Also, you cannot wet lube with Teflon patches.
Just my 2 cents worth, and I hope it helps you a little.
God Bless, Marc