It was my understanding (and maybe I'm wrong) that level 4 plates were rated for everything that a level 3 can take, or 1 round of 30-06 AP. Obviously that doesn't mean you can shoot the 4 with a ton of .223 AP and then expect it to stop 30-06, rather that if it's rated to stop 1 round of 30-06, it'll stop multiple rounds of 5.56 also. Again, not an expert, but that was my understanding of it.
Edited for grammar.
The name on the left side of your chest represents who you work for. The name on the right side of your chest represents who raised you. Make them both proud.
Last edited by msu_grad_121; 11-13-2011 at 21:47..