Back in the 90's, when I shot USPSA, we used to disable Slide Stops, we didn't want slides to lock back, On purpose.
When IDPSA came about, we needed Slide stops to work,
I had that happen a couple times, and every time, it was ME, hitting the Slide Stop with my Strong Hand Thumb, My thumb was too close to the pistol and happened every time I did that. When I adjusted my grip, never happened again.
The 9x21 was back in the early 90's, nobody shoots that now. And Open is getting smaller and smaller every day.
I like shooting the Comp Echelon though.
Thanks for your comments!! I love all my Springfields, they do put a lot of effort in quality control, when they put out a firearm, you know they spent a whole lot of time and effort to make them right!!