Bullets: Any of the poly tipped (Hornady, Nosler, Sierra), the Hornady SXSP, Sierra HP or the Speer TNT are good choices for visual effects on diggers. I personally settled on the 50 TNT in my 222's and 223's for diggers after trying everything from 33-55 grains in them.
Loads: Will depend on what weight bullet you decide to go with, the bullet ogive and seating depth.