Distance the non-backed vest from the body
NOTE: In the early days when the military did not supply bullet-proof jackets, some of the guys purchased their own, and would wear this over the flak jacket. Several guys got shot and had real good results. This would confirm your thought about...
Stretch Armstrong in your pocket
When I was a young Marine, we played around with shooting at body armor with different objects behind the vest. We were always surprised at what worked and didn't work. Like using a fire ax to get through bullet-proof glass...worked the best.
With body...