20 March 2018
The incident that I was referring to happened some years ago when I was adding strips of paper towel to clean the media in a vibrator tumbler while cleaning 308 cases. I didn't take the time to look into each case at the time but went ahead, dumped all the media out of each case, deprimed and primed. Nothing unusual. But when I dumped 15 grns of 4227 the charge nearly filled a case up to the neck. That's when I found a piece of towel lodged inside the 308 case after dumping the charge. Luckily, the level of the powder was high enough in the case to be readily seen.
Quit adding anything to the media except media and relying on the eyes to check powder level from then on. I now check each charged case with a short piece of dowel that is marked when using a single stage press.
Any more that 50 reloads, the Hornady progressive is used with a powder cop die after the powder measure.
Cheap lesson learned.
To the point of this post, After using my vibratory tumbler with new media for a while, I can tell when the media is worn out by the time it takes to clean the cases to the level that I want. When it takes much longer than normal to do it's job, it's time to change the media. Not a big deal.