58 Musket inside primed

Has anyone seen this type of head on a 58 Musket inside primed cartridge. It has a deep cone shaped indent. Maybe to help hold the primer cup in place?

It rather looks as though someone in the past has tried to fire it and, it turned out to be a dud !
M. Rea

It doesn’t look like a firing pin mark. I have a lot of misfires and it looks to uniform.