MVC Truly Log Off With Forms Authentication

I have a logoff action on a controller as so:

public ActionResult Logoff()
{
var x = Request.IsAuthenticated;
var y = User.Identity.IsAuthenticated;
FormsAuthentication.SignOut();
Session.Abandon();
var a = Request.IsAuthenticated;
var b = User.Identity.IsAuthenticated;
return View();
}

However, x, y, a, and b, are all true. So when my view renders, it still behaves as if the user is logged in. Can someone please provide a solution and/or explanation?