For years I used 100 grit I bought a roll14 inches wide by quite long used on shearers metal disks. I cut it and glued with what is called cow gum an adhesive that allows removal.
I now buy whats available its never been critical in number 100 or plus. Pressure you apply, speed and how you present the blank to the paper all important .If there is a gap to be brought down I use the bandsaw first some of our timbers are heavy and hard.
Peter.