I believe you could do this using a symetrical lattice. In the terrain editor, use the blobmaker and paint tools to create a crater-like shape with a hole at the center. Put a wrinkled glass, or even a marbled cloud texture on it or use the texture of whatever object is being hit with a bullet. Use a negative cylinder grouped with that object to create the hole that the symetrical lattice will fit into. For a cool glass shattering into shards effect, you can use a shareware app called DXFBuster. Create a high poly mesh of a rectangle (symetrical lattice works good for this) and export it as a DXF file. Drag and drop the DXF into DXFBuster and it will disassemble it into separate polygons. Import it back into Bryce and group them so the shape holds together until you put it in place. Ungroup it an use the disperse editor to make the polygons fly apart and drop to the floor. It's a lot of work but it's a cool effect.