Magical companion ammo

Magical companion ammo is a type of ammunition in Fallout: New Vegas.

Characteristics
Magical companion ammo is a special ammunition type that companions with a ranged weapon use when no regular ammunition is in their inventory. Magical companion ammo is presumably infinite and hidden. e.g. Boone has an endless amount of ammunition for his hunting rifle, and as there is only his clothing in his inventory, the magical companion ammo is hidden. Otherwise, the player would be able to obtain infinite ammunition.

Locations
A way to get this ammunition is to reverse pickpocket an explosive into their inventory. Alternatively (if you don't want to obliterate them), reverse pickpocketing a weapon and its ammunition into their inventory, then pickpocketing the weapon back out will occasionally yield the same results. It should be noted that Boone's unique weapon cannot be pickpocketed, and will subsequently not appear on his corpse if killed.