Nokta FoRs Gold, a Gold Cube, 2 Keene Sluices and Lord only knows how many pans....not to mention a load of other gear my wife still doesn't know about!
No.
That is where the round touched the breech end which has no where for a pushed reward primer to travel enough to leak...
It looks like corrosion over time.
Good solid primer strike. No evidence the primer was pierced and gasses blew backwards.