That would be my solution, though only some brands of die allow removal of the decapping pin and leave the expander on.
Make sure you didn't crush the cases because you made the mistake of turning the seating die all the way down like a sizing die. That would cause the crimp groove to crush them, assuming these are standard dies.
Another solution, if you intend to experiment with neck turning in the future, is to buy a mandrel die body from Sinclair International and purchase the correct size mandrel to set the case mouth ID and make it round. These mandrels are tapered and will remove indentations as well as set the ID.
The earlier suggestion to chamfer matters particularly for loading flat base bullets. The 14° VLD taper chamfering tools make it most easy, but a standard one should work. Most boattail bullets will slip past even a tight mouth. Keep in mind that the mouth is supposed to be 1 to 2 thousandths smaller than the bullet OD.
I never bothered to do anything to the primed .223 Winchester brass I bought as long as the mouth of the case wasn't indented visibly. However, I was loading moly-plated bullets, so they were dry lubricated. So another thing you can do is dip either the bullet bases or the case necks into powdered graphite or motor mica dust (just before putting the powder in). That will dry lube the seating of the bullet, which may help with your new brass. The bullet bases may be rubbed with some graphite powder on a rag to burnish it in a little. I don't recommend moly powder unless you intend to shoot moly bullets later, as it does affect bore lubrication. Graphite will burn out like carbon and be easily removed by a carbon cleaner.
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