Many times I have reloaded a weapon after refilling ammo, change to something else then back to weapon and the mag is gone. Trying to find it in world with no success. It basically despawns for whatever reason after reloading. Has happened to me multiple times me thinking mag was already too damaged when in reality it just despawns whilst on a gun.

Fill a partial mag, switch to weapon, reload. Switch to something else, back to weapon and mag is gone.

Mags never disappearing even when in ruined condition but still being in the inventory/on the weapon.