Brain trust what do you make of this. My buddy was shooting his SP01 tac with a milled slide by CGW and a DPP. At the end of the stage after the last shot the slide release fell to the ground and the slide moved half way down the slide. The slide stop was not broken or unusual in any way. The recoil spring and guide rod were assembled on the barrel and slide and there was a live round in the chamber. We disassembled the gun at the safe table and everything looked normal. Once it was put back together it shot 2-3 more stages without any issue.
I've never seen anything like that before. Any thoughts how that could occur? The slide stop was snug in the gun once it was assembled again too.