Hollow Point Bullets (10) (5e Equipment)
From D&D Wiki
Any modern firearm which uses bullets for its ammunition can fire hollow point bullets. A firearm which uses hollow point bullets (also known as "dumdums") deals 1 additional point of damage per damage die of the weapon, as the bullets "mushroom" on impact with a soft target and expand, causing larger wound channels. However, hollow point bullets penetrate poorly and cannot strike through armor. A creature with natural or worn armor and an AC of 15 or higher has resistance to damage from hollow point bullets; A creature with natural or worn armor and an AC of 20 or higher, or pre-existing resistance to piercing damage, has immunity to damage from hollow point bullets.
Weight: 1 lb.