I would say a 6 point socket will fit if it's thim enough to go all way down.
It's always a good idea to give the of the screw a few gemle taps with a hammer. If you're still afraid to to round the points give the screws some penetrating oil (or cola).
If you round the points anyway, find a tool that can screw out a wregged bleed nible.
(Eh, in Danish they are called male pig dick)