Here is the full list of all 16 Demons with Shotguns achievements.
You don't seem to understand how ammo pickups work.
Fighting for scriptures.
You used 10 tarot cards in one match.
You jumped 100 times in one match.
You earned a Antichrist kill streak.
You collected 500 souls!
Flawless Victory!
You earned 5 Double Kills.
You earned 3 Monster Kills.
You kept killing yourself.
You're an a' hole with how much you taunt.
You completed Ghosts n' Nomeds.