You said that your bolt opens fine, it just doesn't pull back. Thats because your bolt hasen't actually opened up "all the way". The last little bit of bolt lift is where the bolt cams your case loose from the chamber. This extraction problem is because your case is stuck to your chamber wall. This symptom is especially common with belted magnum calibers.
If you measure the diameter of your cases that stick and compare them with new cases, you'll see what I mean. The pressure ring (just above the belt) is not getting resized enough; and when you chamber a round, your bolt is camming your handloads into a press fit. Read my website, and you'll see lots of tech tips like this that will solve this problem and many others.