Chief Comey said the weapon announced the suspect’s intentions.
“This individual came fully ready to go to war with us. This is not a normal shotgun, this is not a street weapon, this is one meant to hunt nothing other than men, and he took it out on our police officers,” he said.
I take that to mean that a "normal shotgun" is meant for shooting birds, either clay or real, and that an ordinary defensive shotgun with a full length magazine is "not normal".
And/or, it was a cruiser, with a pistol grip instead of a buttstock.