Looks like gas cutting from a leaking primer. Is there a bit of damage to the edge of the ejector hole as well? I would just take the ejector out, chuck it in a drill and polish it smooth.
I did have some partial head separation on 2 cases.
No blown primers that I can remember.
I will leave it as it is until I can find a replacement.
by the way, are replacements available in Canada (savage long action)?