If I owned this rifle, I would try free floating it - knowing that there is a risk it won't shoot as well. When you relieve the barrel channel, be a little on the generous side. Then put some bedding compound (JB Weld is good) under the first 1.5 inches of the barrel and, with the gun assembled, pry the forend of the stock away from the barrel about 1/4" with a small screwdriver - and let it dry.

If that doesn't improve the accuracy (I'm talking lotsa testing here), you might have to resign yourself that it needs forend tension. At that point, I'm looking to sell the gun . . . . but if you don't, you could add the forend tension back back by putting some JB Weld under the forend and prying it away from the barrel with a small screwdriver again - let it dry.