Uneven gas deflection will affect the bullet. Especially if the bullet is almost coming into contact with anything.
I'm expecting this is probably a form 1. Which many people don't do exactly well in the first place and often with insufficient tools.
If you are seeing copper, you're getting a rub and need to open up the bore more. This will both prevent a strike and will improve the accuracy at the same time instead of playing pinball with the bullet on its' way through the can.
When those totally ignorant of firearms make laws, you end up with totally ignorant firearm laws.