Sig p320 x5 legion Screw

I took it out of the gun cabinet this morning, dropped the mag and went to clear the chamber, but it was super jammed, after messing with it for a second i saw this little screw stuck in the gap of the slide. I was able to move it around with my knife and open the slide. the screw then fell out of the mag well, however, i have NO clue where the screw is supposed to go even after watching disassembly videos. The slide feels a little smoother/looser to pull back now. Dont know if this is the right place to post. But o figured it was better to ask than not.