Agreed with comments so far. There is no way that was caused just by a reload.
Pretty much the only way you can screw up a revolver barrel is firing into a squib/obstruction.
Can't tell much from the pics, unless you can get a real close macro of the cleaned surfaces. But that radial ridge in the metal looks scary. Possibly overtorque of the barrel, but it'd really have to be extreme. Improper heat treatment, forming defect, or previous abuse would be my prime culprits. Barrels strike me as something that would generally only undergo sudden brittle failure without leaving metallurgical traces (like say a driveshaft or connecting rod would), so who knows how long it was like that.
edit: well, looks like you guys diagnosed the problem before I finished typing
