While no stinging for me, one weird thing that I noticed is that the needle itself hurt more on my Amo pins. The injection itself was fine, but the initial prick definitely hurt more. The stopper definitely takes more force to push through than other vials I've tried and I wonder if it's dulling the needle a bit, or I just so happened to choose sub-par quality needles from the box for those specific injections. I know this means nothing for those who've experienced prolonged stinging, just an odd observation. Could just be a testament to the quality of my syringes. Using Easy Touch and plan on switching to BD once I go through this box.