Ceramic ESAPI plates issued 04-05 timeframe to the infantry battallions were rated for all 30 cal AP threats. Saw three damaged plates from seperate attacks where the Marine survived each time.
1st plate took a four round burst from AK at contact distance. The ceramic matrix was crushed and had no strength left. All fragments were captured by matrix or the level III backing. Busted ribs. Still in the fight.
2nd plate took a large 7 inch by 2 inch shard from a 155 arty IED edge on. The vest stopped it mid way, capturing it. Basically half in the Marine's chest, half out. Medivac, docs split him stem to stern to fix. He is good to go. Now has a killer scar to tell his grandkids about.
3rd plate attack happened in my presence. Watching rear during patrol as Marine opposite me and behind made the 90 degree turn down a new street to follow the patrol. He took a 7.62x54R round to the center of his rear plate. I was looking right past him when it went down, and saw him drop like a sack of potatoes. After catching a glimpse of the muzzle flash, and directing my team onto a specific taxi, to deal with the shooter. Came back to learn that my buddy wasn't dead, just had a bruise on his upper back between his shoulder blades about the size of a volleyball.
His plate was busted, bullet defeated the plate but was trapped by the level III layer. Rifle was moisin 91/30.