I have some old rifles with really PITIFUL looking bores that still shoot fine,
And some newer rifles that have bright, shiny bores that don't shoot worth a darn,
So you can't go by looks alone!
Shoot it first, see what it's doing, and lapping of any kind is a last resort!
Pushing some 'Scotch-Brite' pieces down the barrel might remove some of the 'Problem'...
I suggest you clean the crap out if it with NYLON brushes and a good strong solvent...
Brass brushes will react with the bore solvents that really work, so they are out.
Using a steel brush in a barrel is a pretty silly idea, since steel brushes scratch the bore when they are new,
Then mat down and do NOTHING to get the crud out of the scratches and rifling.
Nylon will spring back, doesn't round over as easily as steel, is usually angle cut to give good sharp points that really scrub the tight spots where it counts, and don't react to the solvents you need to use for older rifles we all shoot corrosive ammo and heavy jackets out of.
And remember, military 'Ordnance' steel is a little 'Darker' color than the bight chromium steel used in a lot of civilian firearms...
High chromium steel shows up with a little more of a blue tint when it's not highly polished.
(refraction qualities of the steel, doesn't have anything to do with the actual color of the steel)
If you REALLY have issues, a very fine grain lapping compound pressed into LOW VELOCITY bullets with copper jackets will be a last ditch effort to save the barrel.
Fire lapping is ALWAYS a last ditch effort to make a barrel shoot right, not to 'Brighten' the bore,
So take it out, see how it shoots off the bench before you do much of anything!
If it shoots like my old M-1 Garand or the old 'O3 Springfield I have laying around here with their 'Dark' barrels, you will be pleasantly surprised!