You might also check to see if there's an extra washer / spacer stuck at the bottom of the compression tube. I don't know the history of your rifle, but if it's second hand, someone may have put a spacer in there for more compression. It's very hard to see them, even with a flashlight. The best technique, which I learned from Nitrocrushr, is to put a little thick grease on the top hat (which is mounted on your spring), and push it (the spring with the top hat) down into the tube until it bottoms out, then lift it back out. If there's a spacer down there, that should bring it back out.