The AUG A3 is described as:
An accurate, compact assault rifle
You can pick this gun up in north-west Barvechos province, near the border with Mojocoyo, in Barvechos Base. The mission “The Bank Heist” is nearby. The weapons case is in the armoury towards the north of the base.
Unfortunately, there’s a drone jammer next to the armoury, but if you approach the base from the south, it’s open with no gate and you can pick narcos off one-by-one as you work your way towards the weapons case. Just beware of the alarms.
This AR is rated well for handling, only bested by the SR3M. Generally, it’s a good all round assault rifle.
It has a 20 round standard magazine, and accepts the 30 round PMAG extended magazine (available in La Cruz). Try it if you like something that’s versatile, but I prefer to minimise reloads and would look to an AR that accepts the larger 50 round magazines.