I have my own guess as to why the Gen3 22 40 S&W has/had the FTFeed issue when a light is attached to the rail on the dust cover. Dust cover flex.
When the pistol initially recoils the slide moves back toward operator/user and this same recoil causes the dust cover to flex down. Once the slide reaches the end of its travel going back the compressed recoil spring causes the slide to travel forward and the dust cover flexes up for a fraction of a second impeding the travel of the slide going into battery. Attaching a light amplifies the flex of the dust cover.
The use of magazine springs with more coils retards the slide velocity to the point that the dust cover upward flex is more out of time in relation to the slide going into battery. Overall this may address the issue of FTFeed but I think it’s a workaround rather than a solid fix.
It was an interesting thought to me regardless.
When the pistol initially recoils the slide moves back toward operator/user and this same recoil causes the dust cover to flex down. Once the slide reaches the end of its travel going back the compressed recoil spring causes the slide to travel forward and the dust cover flexes up for a fraction of a second impeding the travel of the slide going into battery. Attaching a light amplifies the flex of the dust cover.
The use of magazine springs with more coils retards the slide velocity to the point that the dust cover upward flex is more out of time in relation to the slide going into battery. Overall this may address the issue of FTFeed but I think it’s a workaround rather than a solid fix.
It was an interesting thought to me regardless.