He may have a point.

I had a Marlin 1894 Cowboy with 24" barrel and Ballard rifling, the caliber was .44 mag. I shot only factory smokeless ammo. A friend on mine who had one just like mine except in .45 Colt told me not to really clean the rifle as I would not be able to hit the side of a barn standing in the barn.

I found out he was right. I would remover the bolt and clean it and wipe the down the bolt face but I never really cleaned the barrel. I would just use an oil patch down the barrel followed by dry patches to remove the loose residue but that was it. If I cleaned the barrel by removing all the copper with a brush and bore cleaner until the barrel shined I could not put any rounds on a man size target at 25 yards. As long as the barrel was dirty the rifle shot reasonable well.

I talked with one of our police snipers out at our range one time who had just come back from a sniper school who said the schools sniper rifles were never cleaned until after all the classes were done for the year. Bolts were cleaned and dry patches run down the barrels to remove the loose stuff but that was it. The school claimed to many rifle were ruined from to much cleaning and by cleaning I mean the extreme cleaning that many of us were taught to do.

Sinclair says the same thing, the best way to ruin a top barrel is to scrub the barrel spotless clean on a regular basis.

I no longer scrub my barrels. I use Kroil oil to clean the barrels getting out the loose stuff and leave everything else as is. I only scrub the barrel spotless if the barrel starts to lose accuracy because what the heck have I got to lose. Take this for whatever it's worth.