you need to do 4 step reloading. seat the bullet in the 3rd step only. and taper crimp in the last step. If you use a Lee factory crimp die, it will resize the Entire case also. I had the same problem with .40 caliber. the problem is that all of your brass isnt exactly the same length. therefore when you crimp you are over crimping some of the shells crushing them.
10MM Magnum.... tried the rest, now I got the best