You mention loading all six chambers to test.
But remember, on USFA, you can for safety load only 5---load one, skip chamber, load four more, cock hammer all the way back and ease off cocked with the trigger and your hammer will come down on the "safety" empty chamber.
Also remember, by lowering hammer from half cock position instead of full cock you'll start scoring (scratching) the cylinder with bolt/cylinder stop.
If you do load all six chambers, it's only a matter of time before you set one round off when the hammer's firing pin comes down on a live primer. And don't trust the quarter cock as a safety!
And if, as I suspect, the reloads are at fault you may continue to have problems through the entire 500 rounds because of faulty light loads.
And if the reloader was a bit careless as I suspect you might also have some double loads which could cause the cylinder to go KABOOM to pieces.
Last edited by UncleEd; April 18, 2013 at 01:09 PM.