I use my Do-It Arky weedless jig mold to pour 1/2oz vibrating jig heads, using Mustad 5/0 60 degree jig hooks, but I found the hook eyes would crack when I tried to open them to insert the chatter blade.
So I tried heating my hook eyes red hot with my torch, and that made them soft enough to open by driving an awl into them until I got enough gap to put the chatter blade on. That worked, but the hook eye felt soft and ovaled when I pinched it shut with the blade in place.
So I took a batch of the opened eye hooks and put them into my toaster oven for a hour at 350 degrees, the same temp I use to bake my powder coat, to retemper them.
When I pinched them closed this time I felt much more resistance, but none broke, so this is another step in my vibrating jig making process.
Success!