You might use interior ‘circlip’ pliers.
Or failing those buy a pair of cheap longnose pliers and bend them,
using the oxy torch to heat them. Bend them to your requirements and
shape or round the jaw ends as required.
Is this for holding the cones while you file out the metal between
the prongs and shape the prongs?
Exterior ‘circlip’ pliers are reverse action, in other words they
open when you squeeze the handles together. So dont buy them for this
Though they are excellent for breaking open a heated solder joint
David Cruickshank. Australia