I have the Lead Sled as well. On my first trip to the range, Another guy saw me set it up and told me about the cracking of stocks and the flinging of scopes. I put about 20 lbs of ballast(weight lifting weights) on the sled and it worked just fine. I did notice that the front of the rifle was not as secure as I would have liked. I was shooting my Knight Vision. Does the front rest seem to grip the rifle on your "Sled"?