If you didn't already know, .457 balls are made to fit the Ruger Old Army revolver. Maybe this is a sign that you should eventuallybuy one!

If you wanted to try to tumble them down, you could put them in a large coveredbucket with some sand and let them roll around in the car trunk or in a truck bed for a long time until they wear down to size. It's based on the same principle as a rock tumbler [which BTWis also sold cheap at Harbor Freight].
Or rub down a ring around eachone by scrapingit on sandpaper, and load them carefully either into a sabot [i.e. - like the Hornady Hardball loads]or with a patch.
All of the cap & ballrevolvers shave a ring of lead off the ball when they're loaded into the cylinder which makes them a little out of round, and they're still capable of excellent accuracy.
Or you can alwaysmelt them downand cast them into something else if you don't sell or tradethem.