Why the hate for the ASH-12?

I recently took a look through all of the guns in the game to see which ones I haven't used very often, and stumbled across a gun I have not found a single person using in the last 2 months I've been playing this game: The ASH-12. Curious, I looked up the stats for the ammo and found that it is the hardest hitting ammo in the game. The armor piercing ammo demolishes tier 4 armor and still deals over 100 damage! So now skip forward a week and I've been abusing this thing; a super hard hitting very quiet hand cannon that absolutely wrecks anyone, and for a very reasonable price. I've been one tapping high geared players on factory game after game.

I tried looking up the reason no one uses this, and found only a single reddit post from a while back that didn't seem to even closely fit my experience with this rifle. so can someone here explain why you would prioritize other weapons over this if you are going into a reasonably close ranged situation?