If the mags are in your inventory, then reloading is slow, as you basically take them from your backpack.
If the mags are in worn ammo pouches or in a vest, then reloading is quite fast.
To put mags in certain vests or ammo pouches, you have to 'a’ctivate the vest (or any appropriate clothing item), and then choose a mag.
And no, you can’t see at a glance which clothing items can hold mags, but their descriptions usually hint of the mag-carrying ability.
Some mag-compatible clothing:
- chest rig
- tactical vest/rig
- various ammo pouches
…aaaand that’s all I can remember 
Someone please continue that list.[/quote]
Leg pouch
ankle pouch