Gentlemen;
It is my (tested) contention that regular cleaning of a rifle used in shooting cast bullets is totally, that is TOTALLY unnecessay.
That being said I'll qualify the statement by saying that the load being used has to be, (as we all strive for anyway) to be accurate and non-leading in the first place.
I have fired thousands of rounds, counted on purpose through a given rifle and compared the first group to the most recent and found no difference in performance.
The only thing I have found is that if the rifle stands idle for a week or two it will not shoot as well as it would if used more regularly. That is, if you fired your favorit load pretty much on a regular basis it'll be as accurate and reliable as you can shoot and it will be that way pretty much forever and never a cleaning rod to get in your way.
I realize that I'm going against the usual custom of cleaning practices but try it for yourself. Save all that cleaning-rod time and spare your barrel the unnecessary wear from excess cleaning-rod use; clean only when you anticipate putting the gun into moth-balls for an extended period of time.
Good afternoon, Forrest