I plan to have a competition-oriented shotgun built out for me. Right now, I'm trying to decide between Dissident Arms, Hayes Custom Guns, or Hawkeye Ordnance. I wanted to first ensure there isn't anyone local that can do it, but no luck there so far, so I'll probably go with one of those three known entities.
Until then, I'm using an old Remington pump. Not exactly competitive, but it'll be fun nonetheless.
I'm surprised the make of the gun would make a difference. I figured everyone using over the counter shot shells would be gravitating towards the same charge and shot size.