I'll just throw in that my dad made several new stocks to replace stocks that were damaged from the use of a lead sled. Not his own of course but friends and friends of friends that had no clue of simple physics. Stocks are designed with the shoulder absorbing the recoil. Scopes are as well. How the company making lead sleds hasn't been sued out of existence is remarkable to me since anyone with even a slight working knowledge of the physics of recoil and impact resistance would know that these lead slad products will eventually cause damage to a firearm or scope.