Back in the middle 1980s, I upgraded the brakes on a car, using OEM-size/spec parts to do it with. New brake drums, of course, were needed. So we got a USA name brand of "good stuff". Well before any off-shore stuff was here in those parts.
Upon installation, stopping was not smooth as the drums were out of round. KNOWING that most parts stores stored brake drums vertically, in the box, I knew why they were out of round, so I opted to drive the car some, put them through some hot/cold cycles in normal use to cure them, THEN we cut then. End of problem.
Even back then, it was well-known that if you did a hard panic stop, then immediately parked the car, with the parking brake fully applied, you stood the chance of warping the rear drums as they cooled overnight. Maybe not bad, but still there. As a result, as I normally parked on reasonably-level ground, no manual parking brake use, but then all of my cars were automatics.
So, to me, knowing how the brake drums are typically warehoused after they are made and then shipped, getting ANY brake drum that is completely round, out of the box, is minimal. No matter what. If it needs to be cut, do so only after you have put some miles on it, like a "break-in" period of sorts.
Of course, the amount of time "in the warehouse" can affect things, too. Less time on its edge on a shelf, greater chance of getting one that is still completely round! Which also means anything that came over in a container, would already have "time" when it gets to its first warehouse location!
Just my experiences and observations, no more no less.
Happy Holidays!
CBODY67
