Matt, the tip is just 1 1/2" ID plumbing nipple.
It certainly should not burn past the inside edge of the forge liner.
Here's another thought - if you leave your burner mounter in a stationary manner to the forge after you shut the forge off, the retained forge heat will burn the tip back if you shut the blower off. It's the cool air blowing though it that keeps it from burning off outside the forge liner edge.
That's why I make mine so easily removable. I shut the forge and fuel off, let the blower run a few minutes to sort of cool off the forge, and then slide the blower out of the receiver so it doesn't burn off.
Nothing on this burner - short of the blower - that you can't get in any plumbing store.
This is the same blower running two different forges: