Try a hot air gun it may have loctite or another product. Or soak in penetrating oil for a few days.Take your time it will come out.
Velocity is thrilling, but diameter does the real killing.
If nothing else, it is unique.
You might heat the screw with a soldering iron....just a thought.
JM "Jenuine Marlin"
I think it looks great (and very interesting).
I'd jump on it and hold it with both hands, so no one else gets it.
That one would be fun to go through and research. I took a chance on what appeared to be an unusual S&W 629 a few years ago. It turned out that only 15 were made in a special run.
-NRA Endowment Life Member
-Smith & Wesson Historical Foundation
-Smith & Wesson Collectors Association