Can anyone explain what I'm doing wrong? Also not loading for 12 guage Stoeger. Have I missed a GRA shotgun?

No GRA shotgun just a bug it seems. Try unequipping/reequipping the weapon or even dropping it and picking it back up.

Are you on the PC and using a mod that edits ammo form lists? (FOOK's DLC module for example.) If you are, update your bashed/merged patch. I had the problem and it fixed me right up.

If not, you might have run into a bug.

A conflicting ammo list in a mod is the most likely culprit.

GRA 12ga Dragonfire and Flechette ammo works fine on a modded "regular" hunting shotgun ++ on the PS3. Don't have Dinner Bell on my current play though yet though...