This dent would be considered un repairable by any good gunsmith specializing in barrel work, doubly so because the barrel is forge welded ( so called damascus or laminated steel). The metal has clearly ruptured at the edge of the dent, this terminal weakness won't be fixed by raising the dent. If it truly does not show inside then the bore has been rebored/honed without raising the dent first, leaving a thin weakened area which is also unsafe and is not something that any responsible gunsmith ( or amateur) would do.
Too bad, move on.