Not chambering, action-bar & breech problem. HELP!

[MtnMoonDog]

Hello, my uncle's 870 Express Magnum 2008 is now in my possession. I am having difficulty chambering shells. I've narrowed the problem down to the action bar and breech assembly

The action bar does not seem to be sliding back far enough for the ramped edge to release the shell latch. I can press the shell latch down with my finger, but the action bar and entire forend still won't slide any farther back. So, its not just getting caught on it.

Now if I remove the breech bolt, I can get the entire forend/action bars back far enough to engage/release the latch. It also works with just the slide on the action bars too... only with the breech bolt in do I have the problem.

Can the breech get caught or hung-up? or maybe something is not right with the trigger assembly, catching it? The pump action feels smooth with no resistance/catching. It just honestly doesn't go back far enough. I'm very confused, as I can see the issue. But I have not been able to pin-point the cause for a fix.

Are the action bars different lengths on different models, like a 3" vs only 2 3/4? I think the stock and forend assembly may have came off a different 870. (I remember this specific gun having wood instead of synthetic during my childhood).

If anyone has any ideas or experienced something similar, I'd be very appreciative of your input. I'll update the post if I have any break thoughs.
Thanks for help!

[Scorpion8]

Howdy and welcome. Some pics would help. No, the action bars are the same for all length of shells, only the chamber size and eject port size (I believe) are changed. Check to see if either of your interior latches have moved. Perhaps your ejector is bent?

[Banshee]

Howdy and welcome. Some pics would help. No, the action bars are the same for all length of shells, only the chamber size and eject port size (I believe) are changed. Check to see if either of your interior latches have moved. Perhaps your ejector is bent?

A picture would be most helpful! Something is bent, broken or assembled wrong. The only difference in 2-3/4 and 3 inch guns is the chamber and ejector. Receivers are the same.