if a guy is using level 4 ceramic plates, how important is it to have level 3 kevlar backers to prevent soft tissue damage?

what about level 3 ceramics?

basically, will 308 fmj cause enough damage to need backers?

YouTube has good videos on this question.

Tagged because this is relevant to my interests

If a plate is stand-alone you do not need backers of any kind. If the plate is ICW (in-combination-with) then you need the appropriate backer for the plate to reach its rated threat level.

A backer will reduce blunt force trauma when used with a stand-alone plate but whether or not the reduction in blunt force trauma is worth the increase in cost, weight, and bulk is up to you. It isn't worth it to me.

If the impacting round is within the plates threat rating you'll be fine. Might need a one or two day hospital trip if you get hit with something big (.308, .30-06) and it manages to break a rib or the like but that should be the worst injury you'd get.

Remember, NIJ ratings were made with the intent in mind of having armor made that would allow the user to not just survive but to continue to move and fight after taking a hit. Most armor now, even if it doesn't have NIJ certification (as is the case for a lot of "special threat" armor) is made with that same intent, to keep the wearer mobile and fighting even after taking a hit.

In summary, a IIIA backer behind hard stand-alone armor plates is, in my opinion, something that adds too much cost/weight/bulk for little real benefit.

Cake summed it up nicely

i should have stated the question better, your 2nd paragraph was exactly what i was looking for. thanks.

Also worth mentioning, going to an ICW plate to reduce bulk and weight over a SA is almost never worth it when you consider the soft armor.

I have a IMTV and the way I look at it is this. While I doubt It would be fatal if I removed it and used only the plates if the soft armor lessens the blow its worth it to me. I also like to think that if the edge of the plate is hit, the soft armor Kevlar might prevent it from fully penetrating.

Either way the entire setup with plates and soft armor is a hefty 30lbs and when you add mags it gets to be a heavy ass vest and the soft armor only weighs a couple lbs so in the long run, its not going to change the fact that its uncomfortable to wear for long periods of time anyways.

As I understand, if all youre doing is putting a SAPI size backer behind your ICW plate then you are correct. On the other hand, if your SOP or whatever is to wear plates over a 3A vest or something like that then it isnt the worst idea in the world

Having soft armor under the plates also makes the best a bit more comfortable and can keep the plates from sliding and banging around.