Ben,
Here are a couple of links that have several burrs. There is no grit "size". Just listed as coarse, medium, fine, etc.
http://www.mountainwoodcarvers.com/bits.htm
http://www.woodcarverssupply.com/Structured-Carbide-Burrs-Kutzall-1_4/products/115/
As to which "grit", I'm not sure that changing your "grit" would solve your problem. I would suggest that you slow your speed down and be less agressive when you first start your hole.
Gene