I've been firing a primer off to foul the barrel - does it do the same thing as a shot?
That's all I use the super-hot Federal 209-A primers for.... afterwards I use Remington 209-4 primers. I pop three of the Federals... then load the powder & bullet without swabbing. Vertically, it keeps me the same as my 2nd shot, horizontally, I'm still hitting around 4" left.