I've loaded several thousand primers each in my 5 pick up tubes and only the one that was the best to start with is still the best. It's a pleasure to work with, the others, well, try the sand paper that Economist suggested.
If my stiff ones have gotten better, I haven't noticed. I'm way past thinking they are going to get any better. I'm ready to start reaming them out.
Good luck and if you find something that works let me know.