My initial reaction was that they were consumable. Cheap, expendable, etc.
1. Extra Reloads - has an S at the end. Makes it sound plural.
2. Has encumbrance - lots of consumables have no encumbrance.
This got me thinking that maybe they are sort of semi-consumable. So now I play it as a once per session type thing. Each session, reloads are recharged. There's still reason to have more than 1 if you are really worried about ammo. The encumbrance stat keeps people from carrying a dozen of them to be immune to ammo issues.