We use them underneath the armor on our Plate Carriers, I'd say yes to avoid internal organ damage or broken ribs. Buddy of mine is a 240B gunner, took an AK round in the front plate from about 50m, still left a helluva bruise and knocked the wind out of him.
Cpl Williams, Evan T. USMC, 08FEB2010 ~
D Co, 4th CEB, Engineers UP!! OEF 21JUN-20SEP2011
REV. 19:11 And I saw heaven opened, and behold a white horse; and he that sat upon him was called Faithful and True, and in righteousness he doth judge and make war.