Shoot it in a match. When you have a "0" running and when a round goes south, you found it....
In my experience, there is no way but to try again.that 30 BR case I fully annealed got mixed in with my others. I'm still here writhing about it. I think it's in a batch that has been fired twice, at least, but couldn't identify it from the others after it was fired and re-sized. coreball
Pete