Bobblehead - Small Guns is a Fallout 3 item, a Vault Boy Bobblehead. It permanently improves your character's Small Guns skill by 10, to a maximum of 100.
Location
The Bobblehead is located in the National Guard Armory within the National Guard Depot, sitting on a shelf in the sealed storage room in the basement. It is immediately before the room that requires the Keller Family Transcripts. You do not, however, need them to access the room with the Bobblehead.
Videos
Obtaining Bobblehead Small Guns [1]