Yank:
That wedge looks bloody well full out -- but it's held in by a tiny pin that runs vertically down through the slot which can't be got at easily from the outside. Try this if you haven't already:

Push the forearm back toward the action as you pull the forearm tip outward.

Push it forward as you try the same maneuver.

Also... Try sliding a small well fitting screw driver into the wedge slot that is open and get a bit more leverage to pull away from the barrels. But go GENTLY on this bit. If it still won't come off, see a good smith. You don't want to damage that forearm.

I suspect a burr on the iron or a bent loop is hanging things up.