Moon destruction backfire

#1
I found a link in the forum that calculates moon destruction chances, and backfire chances.

it seems the program is a little bit old, so I wonder if this is STILL correct

a 9k moon as a 47~50% chance of destroying attacking RIPs (backfire)
a 8k moon and up has a 45 ~ 47% chance of destroying attacking RIPs


sounds about right??