One thing I'll throw out - if a barrel is "burned out" (end of total life or accurate life for a use) and you're committed to getting a new barrel: you have absolutely nothing to lose by trying new and aggressive cleaning methods. That's a great time to try out one of the abrasives or harsh chemicals that would just absolutely destroy a barrel in it's prime
So pull out the JB or Iosso, grab your felt pellets and have a go at it. Go full-on
and chuck up a carbon rod in a drill with a bore brush, and go to town on stripping that thing down to the barest of metal. Run a set of Tubbs Final Finish through it, and see what it does.
It's a loss anyways right? All you have to lose is some time and a little bit of effort, but you stand to gain challenging common preconceptions. And if Iosso and a nylon brush really does carve canyons through your rifling, you can forever lord it over the rest of the peasants that have never sacrificed a barrel for winning an internet argument.
Oh yeah, 100%. This is why I have a 223 AI, the barrel life on that thing is measured by my attention span more than anything else. I'll get bored of it, or decide to not buy another lot of brass for it before it burns out. Gives me something to shoot while the boomer is cooling down. 22LR and 300 BLK are also great high-volume shooters, they're the most fun I have on some trips. When nothing is going right with the 6BR and life sucks I can pull out my 22LR and go 'ding-ding-ding' at 300 to remind myself I'm not a total idiot
This is a really good reason for people who think they can't afford to "build" a rifle to stop buying off the shelf to change calibers. Get a good action, and get it bedded into a good stock, then you can change out barrels whenever you need to. Impact Precision and Defiance both have shouldered prefits available, and both companies sell replacement bolts so you can even change the bolt face size with a new barrel just as easy. There are so many actions with 0.001" headspace guarantees now that shouldered prefits not only are common but work great, you don't have to mess with the Savage/Remage anymore if you don't want to. If you don't mind a Remage, there's no reason to not bed even a factory action into a good stock and have a life-time hunting rifle that is multi-caliber capable.
I could really wreck some minds by pointing out that some benchrest guys epoxy their actions into their stocks, and change barrels without taking the action out ever again.
They aren't exactly running mass produced prefits, but essentially they're running custom pre-fits based on the measurements of their last barrel. Some smiths are good enough to not even need the rifle in-hand to fit a barrel, they take good notes and trust their work.