Thanks - that clears up that it's not M4 or something difficult to get.

I'm fabing my own wall mount cleats with ~20 degree left & right toe in. They will be mounted above my 46" LCD; L-C-R will be vertical with tweeters at 57". Surprise that it works out as owner's manual recommends. Looking forward to see if I can get them to sound as good as my main system. Maybe even better integrated.