Just because a plate stopped a bullet, doesn’t mean the plate then distributed that force evenly across it’s whole surface. The bulge on the back side of an impacted plate doesn’t form gently.
Backface soft armor also catches spall, which can be very dangerous itself. Even ceramic plates can have a danger of ceramic shards. I believe modern ESAPIs, XSAPIs, and such modern plates are designed stand alone, but original SAPIs carried a warning that their rating was only in conjunction with soft armor.
Just because a plate stopped a bullet, doesn’t mean the plate then distributed that force evenly across it’s whole surface. The bulge on the back side of an impacted plate doesn’t form gently.
To add to your point, trauma pads exist to help mitigate this. Blunt force trauma is no joke.
Backface soft armor also catches spall, which can be very dangerous itself. Even ceramic plates can have a danger of ceramic shards. I believe modern ESAPIs, XSAPIs, and such modern plates are designed stand alone, but original SAPIs carried a warning that their rating was only in conjunction with soft armor.
Maybe on a plate from 1965 that is just a sheet of steel inside cloth. Modern ceramic plates spread the energy of the impact.
Here’s a video of a Level IV plate taking a 30.06 AP round followed by like 6 5.56 AP rounds and a 7.62x54R AP round so powerful it jammed the rifle.
There’s no significant plate bulge even after all of that.
https://m.youtube.com/watch?v=D1qLZwBeMuM