ITEM DOES NOT INCLUDE A MAGAZINE.
The Caliburn is a Mag-Fed Pump-Action Homemade Blaster design released as an Open Source Non-Commercial license file set by Captain Slug.
Recommended spring for most consistent performance: K25
It is compatible with official Hasbro HIR ammo, but aftermarket ammo of the same type might be unreliable given their wider diameter distribution.
Color Configurator: http://www.captainslug.com/nerf/caliburn/r/