Here is my solution, a piece of 1/2 thick AR500 in front of the box.
View attachment 1402013
This is not foolproof, looking at the white cable coming out of the right side, there is a hole in the panel caused by a faulty bullet landing sideways right on the cable. I replaced the cable.
As a safety concern, to possible people being in the pit area, I removed the AR500 plate, so there could be NO possibility of a projectile hitting it, and shattering and endangering any people or other items in the pits.
I then mounted the box on end, to provide a smaller cross section, and reduce the possibility of a strike on the box.
View attachment 1402016