Solved my issue
My factory M&P came with suppressor sights and a threaded barrel. With my AAC Tirant S and Griffin Armament Camlok adapter it would not cycle 147g 9mm. Bought this spring kit. Had to remove the nut on the factory guide rod and leave it off. This isnt uncommon in some of my other handguns. The springs dont allow you to keep the guide rod and spring as an assembly but it also makes it easier to change as needed on the fly. I worked up from the lightest spring and the 15lb was perfect with enough return spring weight to close the action.
