I have a M&P full size forty. Put a Apex trigger in. Now the takedown lever falls out when the slide is off. What happened? Pistol still shoots as before. with a much better trigger. john
I expect you lost the little spring that retains the take down lever. Brownells part number is 940-000--956AU, takedown lever wire. You aren't the first, you won't be the last to do so.