Ringed/bulged bores are caused by the pressure and not the bullet/shot charge/ball. A rifle barrel fired with an obstruction such as a stuck bullet, slug of snow, mud wasp nest, dirt or whatever will often not be damaged where the actual obstruction is, the damage will be at some point prior to the obstruction. Look at this picture and you'll clearly see where the barrel bulged prior to where the actual obstruction was, the bulge took place first and when the barrel reached its maximum elastic point then it started splitting.
Anything that causes the projectile to slow down will cause the pressure behind it to raise considerably and very rapidly. It has nothing to do with heat because the barrel steel cannot absorb enough heat fast enough to have any effect on the failure area. This is why a shotgun barrel plugged at the muzzle will often shed a portion of the muzzle end - the pressure spike causes the thinnest portion of the barrel to fail first many times resulting in the portion being torn away and the remaining section flared and/or split.
The end result of any failure is directly proportional to all the factors involved. Certain powders used under certain conditions can also cause a barrel failure giving the appearance that a bore obstruction was involved even though it was not - this is commonly referenced as "SPS" or Secondary Pressure Spike that is caused by the nature of the powder burn itself. During an SPS event, the bullet itself becomes the obstruction simply because it cannot increase its velocity to match that of the pressure rate of rise behind it.
I often hear comments being made about barrels having symmetrical splits from a failure - first thing is, most rifle barrels do not have rifling grooves that are deep enough to cause a "zipper" effect but deep exterior profile flutes/cuts can have somewhat of an effect on the direction of the failure but it all depends on where and how the failure is initiated. If you look at the picture above, that is about the best you can ask for in a catastrophic failure - the barrel peeled back somewhat symmetrically and it doesn't appear that any large chunks were lost. A barrel that peels rather than fragmenting is a blessing because it usually allows the pressure to vent off in directions out and away from the shooter - if something is going to turn loose, that's about the best outcome you can ask for.
Back to shotguns, look back to the 1990's when some people tried shoving big steel shot pellets through bores with full or tighter chokes. The classic failure didn't start at the choke but rather some distance prior to the choked section and when the failure was properly reconstructed, the point of origin was at or near the powder-end of the wad column where the pressure from the powder burn exceeded the strength of the barrel. In some cases a failure will be nothing more than a small bulge and split that allowed enough pressure to vent without a complete catastrophic failure occurring. In other cases, the shotgun barrel opened up much in the same manner as the rifle pictured above. I bought a 12ga Steven singe barrel, the 30" bore was plugged with mud when the previous owner fired a 1.125oz load of #8 lead shot (Winchester AA trap load if you're curious) the last 10" or so on the muzzle end opened up like a flower, perfect symmetrical pattern with the bulge section as seen above.
BTW - you can swell or ring a barrel without it breaking - that is the most common definition of "ringing" be it in the bore or chamber.