Trapper is correct. IF you insist on doing this, just get a piece of plumbing pipe long enough for the rod, thread the ends for end caps, and fill it with kerosene, or lamp oil. put the rod in there, and close it up and set it aside for a couple of months in your workroom or garage. It is kerosene, so keep it away from fires. When it is done, remove it and let it air outside for a few days. Wipe off the kerosene, but let the rest dry out of the wood over sevral days. If you pick it up with some napkins or paper towels, it should not leave a stain. At that point, you can stain it, and cover the surface with your favorite wood finish.
I don't see the need for anything other than a straight grained piece of hickory. The wood is tough enough, and will last several life times, if it is cleaned and finished once and awhile along with the gunstock. Use a hand over hand tecnique instead of trying to seat that ball with one big stroke, and you won't break any more rods. The one big stroke technique comes from watching people using military replicas and steel ramrods. Wood is not steel, and you are not loading a smoothbore musket. A rifle demands extra care in loading so that the ball is not distorted by the process, and flies true when the gun is fired. You also don't want to tear cloth patching, which can be done running the PRB down the barrel too fast. And, remember, if you have the right Patch and ball combination, there will be air in the barrel under the PRB that has to escape- usually out the vent or nipple behind the powder. That one big stroke technique sens a lot of your powder charge out of the barrel, and the amount varies from shot to shot. In a 75 cal. musekt, that is smoothbore, accuracy is measured in minutes of man. In rifles, it measured in minutes of angle. Use a different technique when loading a rifle using a wooden ramrod, and you will be a happy shooter.