Bought a used Contender about 6 months ago and decided to take the barrel off today. Can't. Pulling the trigger guard all the way to the rear does not release the barrel. I managed to get the hinge pin out but barrel will still not release. The barrel will actually slide forward a bit but won't rotate. What is wrong, why did it happen, and how do I fix it?

Without more details best I can do is guess.

Probably a one piece locking bolt barrel on an "Easy open" frame. You will have to push out the trigger group pins to remove it and the barrel will come off. Then call TC and tell them you have an older barrel with one piece locking bolt and you need a split locking bolt. Install new split bolts and your problems will go away.

That would be my suggestion as well. Give it a try and let us know if it solves your dilemma.