Thats actually what i was going to try first. I have the RCBS collet puller so i have just going to try a light tap and then reseat to the correct depthDouble check the concentricity, the impact combined with brass hardness & neck tension may change something. If your collet puller will pull them without "marking" them it might be better.
If you have to pull them all down with the impact stuff a couple of patches in the bottom to protect the tips.
After pulling the neck tension always seems lighter so I resize for my own peace of mind.
Anyway good luck on the competition.