Yimmy do what the guys are saying. first, get one of the rounds that does not chamber. Pull the bullet. If you don't have a bullet puller, put the loaded round into your press and run it up to the top without a die in the press and grab the bullet with a pair of wire cutters. As you lower the ram the wire cutters will go across the press and you can pull the bullet out by continuing to lower the ram.
Next, dump out all the powder and insert you sizing die into the press. Back out the decapping pin so you don't touch the primer but your expander ball still enters the case. Lube the case and run it though the die. Be sure your die is set to contact the shell holder plus 1/8 turn more (It will feel like the ram cams over the die base.
Try to chamber the empty case.