If a fragment pierces one of the IED resistant Shrapnel Shield TM ballistic inserts, will it still do me any good to have been wearing the BCU?
That depends on many factors such as how close you are to the blast, the size of the fragment (s) that impact the Shrapnel Shield TM ballistic inserts, and their velocity upon impact. Overall, the answer is yes, as the damage the fragment causes to your body will be less severe as it could be moving slower after penetrating the Shrapnel Shield TM ballistic inserts.
