To me the 'secret' is in the grain. Check out information about ladder rungs. What is true for ladders is true for ram rods. If the grain runs all the way through the ram rod, it won't want to break when one bears down on a load. Certainly, keeping the wood soaked with oil, and pliable can't hurt. A wooden ram rod with the grain running from end to end will be less liable to break under stress. Just an old carpenter' opinion.