Many gunsmiths drill and then bore with a bar, then finish up with the finish reamer. How the reamer is piloted does make a difference. I use reamers with removable pilots, only. I have a selection of pilot bearings for each caliber, and choose the pilot that fits the bore the best. Fixed pilots are slightly undersized, so they'll fit every barrel they're designed for. Also, with a fixed pilot very small cuttings can work their way between the pilot and the bore and do considerable damage. Some gunsmiths just use the finish reamer from start to finish. I have always drilled and pre-bored, as that was what was taught when I attended gunsmiths school. 30yrs ago. For most shooters, a SAAMI speced chamber is all they'll ever need, as a quality made barrel that's been properly chambered and then the metal properly bedded into the stock, with a good trigger and optics, will out shoot 98%-99% of the shooters out there. I have never tried a fixed pilot finish reamer, with oil grooves, in a barrel using my muzzle flush system. With clean cutting oil force fed from the muzzle end through the barrel to the cutting edges of the reamer, maybe chip damage would be eliminated,,,, maybe. Good barrel blanks cost too much to do much experimenting with....... But I may try it some day.