I load some “off brand” bullets. Got bit once. A load listed as “safe” in Hornady was over pressure in the generic Remington bullet I was using. Actually had a nice chat about it with a guy at Hornady.
Also, the old books are out of date. Go to a store and pick up the current edition of each book (or just look at it). Powder formulations change over time, and a lot produced in 1985 will not be the same as a lot made 2018.
I think some of you are hitting on the issue here. But then why don't they call it Unique II or something?