Many of us serious home defender types, hoping to NOT have to face a rabid mob of antisocial "Orks
" let's call them, will opt for a rifle that chambers something like the .308 or .300 Win Mag, both of which will punch on through about 4 or 5 current issue helmets before slowing down in the brain of the last one in that lineup!
BTW, I'd hope you folks have some community defense organization going, at least among the like-minded, since to defend your home territory all by your lonesome would be a bit trying, especially if the "Orks" do even the minimum of planning!
Heck, if I, on my own, wanted to "take" a home or it's resources, even one that was supposedly well defended, I'd just pick off the defender(s) from about 600 m away with my scoped M1A NatMatch when they least expected it, then go away for a day or three, then come back, repeat, and so on, until they run up the white flag!
I'm just sayin'... Helmet or not!