The ejector rod shown is a later vintage part than that barrel. There should also be a number on the bottom of the barrel that matches the S/N on the butt of the grip frame. If it doesn't match, the barrel is a replacement. Check the back of the cylinder too. It should also have the same number as the butt. If they don't all match, your gun is essentially a "Franken-gun" and may need more than a spring to function correctly - and safely.
S&W Forum Member #721