Buckslayer

Buckslayer was a pre-War ammunition brand of Shotgun Shells.

Gameplay
The shotgun shell is common in the Capital Wasteland, the Commonwealth, Mojave Wasteland, and Appalachia, as they are carried by all enemies that use any shotgun weapon. These 12 gauge shells are marked as being 2 3/4" shells using 0 buckshot.

Product description
The box reads:

Appearances
Buckslayer brand shotgun shells appear in Fallout 3, Fallout: New Vegas, Fallout 4, and Fallout 76.