I had a factory round fail to go bang. Pulled the bullet, emptied the case and had the primed case (with a nice firing pin strike dent in it) lying around for a wee while. I had tried to fire the primer in the empty case in my rifle a couple of times but no go.
So I deprimed and sized my old brass last night and, oh so gently popped the unfired primer out of the case.
Retrieved the primer, placed it on the garage floor, safety specs on, and whacked it with a hammer.
It did indeed go bang.
Taught me a bit more respect for primers!
(PS ear defenders would also have been a good idea)