When I worked with the late Jim Cirillo on several instructional videos, he explained that after his first gunfight on the NYPD Stakeout Unit, he switched from the issue 168 gr RNL to full wadcutters. The reason was that two of the first three rounds he fired that hit the head of the first perp failed to penetrate the skull. He carried wadcutters for a while before switching to Super-Vel hollow points, but still liked wadcutters because of their "cookie cutter" behavior on bone. He also handloaded them upside down to take advantage of the shallow hollow in the base of the bullet for expansion.
He later developed an amazing round that was basically a solid copper wadcutter with a slot (just like the slot for a flat-bladed screwdriver) in the face. The slot accepted a plastic insert with a round nose to allow the round to feed in an auto. The plastic flew off when the round left the barrel and the slot acted like a hollow point. Rather than mushrooming in all directions, it peeled into two huge petals. In an article he did years ago (I think for Handguns magazine), he showed he was regularly getting .45 rounds to expand to more than an inch across.
He was an amazing man and an incredible shot. I miss him.
Stay safe,
Mike