I will save you a bunch of time. Grind the wood screw in front of the trigger guard down. Like an idiot I did not read directions and spent about one hour longer than I should have screwing with my 452 because the sear would not engage. Finally read the directions and found that the center screw was actually hitting it. Grind Grind Grind Grind. I will recomend automation Solutions sear worked very very well for me.