So, will it work to take the front sight off my bayonet lug shy front sight and replace it with one with a bayonet lug?  Not something I think I have to do, just something I might want to do someday when I feel like messing with it.  I've heard it is not something easily done but it looks like it shouldn't be that hard.  Just drive the roll pin out of the gas tube and then the pins out from beneath the barrel.  Am I mistaken?

they don't drill the front sight pins in the same place so no you can't swap one to the other.

you need to buy a new barrel with sight tower.

Crud.  I was hoping you weren't going to say that.  It's not worth buying a new barrel just for a bayonet lug to play with.  Barrel's still fine after several thousand rounds of ammunition so I'll just leave it as is.  Thanks for the answer.