i second (third) the sugestion with a footing.
My arrows were already tough, but with my backstop on my indoor training range i had some mushroom or breaking and also inserts breaking (though mine were alu). I footed them with alu shaft 1,5" long, didnt affect the spine but now they are bomb proof!
Just for testing i took an arrow and shot it against the concrete wall from 15 yards 4 times in a row with 57#, i lost three nocks, that was all.
To make even the insert stronger you could file the insert collar down till the footing also pushes over the insert till it touches the point, then glue it with epoxy.