That's a really interesting breakdown, caffeine_me. I didn't catch that the first time around -- thanks for reposting :)For what it's worth, there is one manufacturer of adderall that *seems* to get complaints most often: Corepharma. Also, I believe the 20% variation allowed by the FDA is outdated information (but the facts about this, for some reason, are very hard to track down). I think it's actually a 5% variation now.I have actually seen a warning letter sent by the FDA to Corepharma, stating that they'll be fined if they don't improve their quality control. Apparently they were testing based on batches and as long as a batch had the right purity, they said the pills were good or something like that. The FDA said that wasn't good enough. The take away I got from it is that "it's good enough for my peace of mind, but not scientifically sound." I never really noticed much difference with Corepharma pills though, myself.And it was a short letter without details, and this was like, a year or two ago (and the letter was already a year or two old). Anyway, the point is that either even pharmaceutical companies can't get their standardized doses correct enough to always feel basically the same (so no way small-to-mid-level clandestine manufacturers can be relied upon to do it), or the human body does stuff sometimes that makes it irrelevant and you have to expect doses and your reaction to them to vary at least a little bit.