Quote Originally Posted by Chief80 View Post
I see it serving no purpose. It is solid machining flaw I believe.
Yeah, your fine chief. That is a standard BAS. And yes, that little “nub” is a simple machining flaw. It’s common for sizing screws. The screw is spun while a Tungsten Carbide bit is introduced into the threads, cutting it flush via radial material removal. Any bolt lift will work on yours just fine.