Tubbs is most definitely not
firelapping -- it will not
iron out constrictions in the bore, nor will
it swamp the barrel to get uniformly increasing grip on the bullet as it heads towards the muzzle.
It will merely polish existing surfaces and leave any disparity in dimensions alone.
On the other hand, the NECO system will
firelap the bore -- big time. Given that you start w/ 220grit....
You get the picture.