Slug or Flechette ammunition for Shotguns that pierces armor has been a suggestion passed down for generations to shitty 2238 devs that just couldn't handle adding new ammo (that wasn't the amazing and oh-so-needed addition of .22 Hunter) to their game. I have advocated for a buff to Shotguns through the obvious avenue of more ammo types for a while.
If Kilgore has any intention to buff and add new shotgun ammo types then here is my suggestion:
Change original ammo to Buckshot (JHP):
AC Mod -35
DR Mod 30%
DM Mod 2/1
Add Slug (AP) ammunition:
AC Mod -10
DR Mod -35%
DM Mod 1/1
Armor Piercing
Add Flechette (High AP) ammunition:
AC Mod -25
DR Mod -50%
DM Mod 3/4
Armor Piercing
Add Dragon's Breath (Fire Damage) ammunition:
AC Mod -25
DR Mod 0%
DM Mod 1/1
Modifies type of damage to Fire, is affected by Pyromaniac.
Obviously not all of these numbers are to be taken to heart, it was just stuff left over from a previous endeavour into the FOnline SDK with a few friends. Maybe all this is too much for what is essentially a reboot of featureless and contentless 2238 and Kilgore wishes to stick to its roots, but even so, the addition of just Slugs would help the game a lot.