"High temperature" superconductors have been made that can operate at a blazing hot -150o C. I think I heard about that before the turn of the millenium, and then the story just sort-of dropped out of sight. I'm assuming nothing much new has happened, or we'd be hearing about it. So whatever techs brought the temperature up to that new record must have dead-ended right about there.
IIRC, that breakthrough was achieved with new materials (ceramics, I believe). Mayeb -130 is as warm as these materials can get us, and new materials must be discovered/created before we can go any warmer.
Didn't really understand the comment about dynamite. You mean using dynamite as a superconductor, or blowing up a superconductor to get it up to room temperature, or what?