Most important thing of all in a 412 is, to MAKE SURE that the recoil lug on the bottom of the bbl., is taking the recoil, NOT the buttons on the side of the action that the bbls pivot on!
Those buttons and the matching recess' on the bbls should be kept spotless and then a very LIGHT "film" of grease put on the mating surfaces.
I use synthetic automotive grease, it only takes a film of grease, more is not better...
Lincolns legacy is, he freed the slaves
Obama's legacy will be, he freed the terrorist!