I use a 1/4" dowel about 10" long with the one end beveled at about 45 degrees. I insert the bevel end down and push it as far as it will go, then with the other hand roll the release towards the muzzle and try to lift up on the for-end with the dowel.
Some loops on the barrel where the "J" spring fit have a depression and the "J" spring fits into this depression.
When you get it off, take the for-end wood from the metal and try it back on the gun. This will give you an idea of what is holding it on so tight.
Make sure that the escutcheon screw on the banjo release is tight and that the roller is moving when you roll it forward.
That is my guess on what is making your for-end hard to come off.