Currently the tooltip reads ‘Your Armor-Piercing Shells have a 75% chance to apply Exposed when you hit.’
This is of concern since the main feature of this weapon is the +50% chance (100%) to apply exposed over the normal 50%.
50% more of 50% is 75% though.
Some forum posts and tswdb show how the tooltip at some point read 100%.
- Shotgun of the Howling Dog - This weapon gains more Weapon Power when leveling up. Your Armor-Piercing Shells have a 100% chance to apply Exposed when you hit.