Skull bullet wound analysis. Fragment of bone from the skull of a person killed by a gun. The bullet has passed through the skull, leaving the hole seen here. Typical bullet speeds are in excess of hundreds of metres a second, and they punch a hole through the tissue they pass through. Forensic analysis (here using a light microscope) of the markings on the bone, and the size of the hole, can help indicate the calibre (size) of bullet and the type of gun used. This wound has been produced by a small-calibre bullet. The impact often causes the bullet to flatten and fragment, leading to extensive and fatal damage as it and the skull fragments pass through the brain.