I use a Brownells Stuck Choke Remaoval Tool to get those kind out.
My problem is holding the barrel without damaging it
Last one I did I ended up straintening the vent rib too.
Oh and the guns usually have some sort of dipped camo finish that prevents the use of heat
![mad mad](/forum/images/graemlins/default/mad.gif)
I do provide a disclaimer before any wok commences though ... lol