Occasionally you will find an iron that will
get more stuck as you tap on the tang. This
can be caused by an iron that is not tapered
evenly. This can be caused by an number of
reasons. Poor sharpening habits. Rust and
pitting causing material loss. Etc.

What you may find is, that when you
measure the thickness in various sections,
typically the blade may measure .140 and as
you move to a mid area it will then be about
.100 But then as you measure farther up the
tang it will increase again to .120 !!!
This will cause the iron and wedge to bind as
it actually should be loosening. In which case
you will need drastic measures to remove
the wedge without damaging it.
Stubborn Irons