It's been a good six years or so, but I took a case of Blazer Brass .45 to a class at Southern Exposure (in Florida), and had a host of problems with bullets retreating into the cases on recoil, causing failures to feed. I had plenty of spare ammo (Blazer aluminum case) to finish the class with, and Federal sent me a case of new aluminum case ammo as compensation for the problems I had with the brass cased rounds.
There were at least two other people in the class who had previous similar problems with Blazer Brass in .45. I've probably shot 5,000+ rounds of it in 9mm without a hitch.
Federal may well have solved the problem with tighter sizing and/or crimps on its Blazer Brass rounds by now. But I haven't used a round of it since that class, preferring Blazer aluminum case or Sellier & Bellot, neither of which have ever caused me a problem in training, practice, or competition. YMMV, of course.