texbestshooter, I have also had a pair of Premier grade grips break under a 454's recoil. It was however my fault, as the grip screw was not checked for tightness before continuing to fire LBT 360 grain bullets. The grips chipped off through the grip frame stud.
I have also had one scope mount screw break off. It was on an old style Freedom Arms scope mount, the left side adjusting screw broke off. Same thing I had not checked for proper tightness before shooting.
I'm not saying that loose grip screws, and gun/scope screws being loose is always the cause of broken screws, but it has played a key issue in my Freedom Arms 83 shooting experience's.
Stevejr454