Disc brake hoses don't fit frame brackets. Grind which one?

I stopped working on cars for a living about 10 years ago. At that time WAGNER hoses always fit. That flat, as you surmised, keeps the hose from turning under several different circumstances, which would tend to cause problems upstream to it.If you cant find the right hose,a well-filed flat should be no poblem, and certainly better than none at all.