I agree that you should not shoot any of the hand loads and pull them all down . If you don't know for sure what the powder is , dump it an use new identified powder.
If you don't hand load then find somebody to pull them down and just keep the case and bullet till you do hand load.
I refuse to shoot anyone else's hand loads it is just too risky .
A good tool for visual internal inspection is a Doctors Otoscope , one of these Pocket PRO LED Fiberoptic Otoscope NO Burned OUT Bulbs | eBay
After some experience with it you can see thinning of the cartridge web starting as a black shadowed ridge right where cases always go.
If you section a few cases over time and inspect the progress of thinning add to that the amount of times already fired and you can build up a mind picture of how much thinning is associated with the look of the Shadow and you get a good visual idea of when they need to be replaced.
I find this more reliable than using any type off feeler to gauge the web thinning as I can't feel it properly and one side could be worse than the other and you miss it , sectioning a few would also help with learning the feeler operation but I like the visual way better , you can see all the inside of the case and check for burrs , pits, cracks and flash hole irregularities when they are new . It's like using a mini bore scope and also great for inspectiong dies .