ORIGINAL: bigcountry
If they are dents,then we call those hydro dents. Too much lube.
One thing you might be doing is when you setup your seater die, you need to screw it in so it just touches your shell holder then back it out completely 1 turn. I see a lot of new reloaders who set it up like thier sizing die and it will crush your case. Built in the seating die is a crimper that causes this.
Yes. You probably have a situation where your seating die tried to crimp the case at a spot where the bullet did not have a groove (cannelure) for the case mouth to crimp into. The case mouth had to go somewhere. So it collapsed the shoulder of the case from the inside out, making it too big for the chamber..... Set the seating die as BC has indicated.