If it's not binding with the trigger group in place, then there is something going on with the trigger group....take a few pics and post them, may be obvious.
Try this. Remove the barrel and forend, cock the hammer, and then drop the hammer slowly until it contacts the firing pin...see how much firing pin protrusion you have out of the frame, and if its at any type of angle.
I'll have to check this on my laptop when I get home....but one thing to try, remove the forend from the barrel, and then reinstall the barrel into the action. With the action closed, see if the lockup is tight between the barrel and the receiver. Lockup should be tight, with no wobble or...