Arduino for Nerf: Chronograph and Shot Counter : 28 Steps (with Pictures) - Instructables
Nerf Dart Ammo Counter Review | Nerf Gun Attachments
Prototype NERF MA40 Mag concept | Halo Costume and Prop Maker Community - 405th
Halo MA40 Blaster Review | Blaster Hub
Nerf gun upgrades! Mod your nerf gun with a Raspberry Pi
Functional Halo MA40 ammo counter test fit : r/Nerf
So this is what the inside of the Ma40 ammo counter looks like. It has a Faux Ammo counter that goes inside of a "window" plenty of mod capabilities. : r/Nerf
Honest Review: Universal Nerf Ammo Counter Attachment - YouTube