I see in the book "Shooting The British Double Rifle" that the author refers to using a lead sled. I recall seeing in more than one place that they should not be used for fear of breaking stocks. I also believe that Caldwell may even say they don't recommend use over .416. Does anyone out there have any experience with them? I am going to try and regulate my .500 a little closer and lets face it a lead sled would make it a more enjoyable process.