When it finally does break loose your heart will skip a beat because it sounds like the screw just broke off.So far, this is what I have to show for trying to take it apart (the black one):
View attachment 788271
(It wasn't originally spiral, it looked just like the other.)
After your experience I didn't use the one that came with it - hoping I can keep it with the gun, if I ever get it loose. If I can find a socket of the same size, I may try it with a short piece of allen wrench (might as well use this one, if there's a piece straight enough).
All the smaller screws came loose fine.
BTW, I did learn that if you remove the left-side grip panel, watch out for the slide lock coming out. Luckily I didn't lose it and got it back in right.
Good luck! Keep us posted.