I just got finished making four ramrods for rifles, starting with 7/16" dowel blanks. They were all seriously warped, in many directions. I used my heat gun, starting at one end, and heated up a foot at a time. When the wood was too hot to touch, I slipped it into my six inch bench vise which i had opened just enough to receive the rod, and bent it straight + a little more. I held it there for about thirty seconds, and then heated up the next 12", and repeated until the rod was perfectly straight, or next best to it.
I tapered them to 3/8" - actually .385" so I have some to sand, using Tom Curran's amazing ramrod tapering plate. As you know with rod blanks turned into dowels, there is always some grain run-out, but the Tom's scraper doesn't care which direction the grain runs, within reason. When I'm close, I sand the rod between two ten inch boards with a V groove cut, and covered with 80 grit abrasive cloth. When the rod fits the pipes, I trim to length, and use the lathe to put on the rod tip on the small end.