Every time I see a thread like this one that talks about such a small alteration to "fit",especially with thinking of bending or sanding, it makes me think back on all of the shotguns that I have owned or borrowed. I have just picked up them and fired, never thought for a second what the cast was. I have bought 20 plus new in the box shotguns (Remingtons, Winchesters, Mossbergs, Brownings) over 40 years and never checked one for cast. Hunted with them all and never had a problem. Also I have never checked cast on any of my collection of Model 21s, Ithaca NIDs, Parkers, Remingtons. LOPs vary from 13 1/2" to 14 5/8" And if shooting in cool to cold weather with various layers of clothing they would all change.
They have drops of 2 1/4" to 3" and I hit with them all. Am I magical or are there others out there like me?? I really believe, like with any subject, you can go off on the deep end!