Automatic Weapons

This is the tree of automatic weapons, it goes from the least good weapon to the best weapon of the category. 

Mini-SMG

First SMG you will encounter, it has a big rate of fire, but a rather mediocre secondary fire. It's a rather flexible smg that will help you climb up to better weapons. Its magazine has 25 bullets, and the reload time is short at around 1,3 seconds

SMG

This is the first fully fledged automatic weapon. It's fast, good.To compensate the big reload, it has a rather big magazine, with 45 ammo. And while the secondary fire is good when you find yourself against an horde of seekers, it's recommended to not use it too frequently, since it's not too effective, and the reload is rather big

Assault Rifle

It's a good weapon, having significantly better damage, at the expense of a lower ROF. It's secondary is good when you have a bigger enemy, since for each shot two bullets will come out. The magazine is standard, with 32, but the reload, is rather long, compared to the magazine size.

Heavy Assault Rifle

It's an excellent weapon, with high damage and a large magazine, with 90 bullets. The reload is even really fast, almost one second shorter the Assault Rifle. Little quirck is that you need to hold down the trigger for a faster RPM. The secondary fire lets you shoot faster, but unless you are facing an horde of enemy, it's not recommended to use it too much

Minigun

The "6 barrel of death"... It's more or less a side grade than an upgrade. It does have unlimited ammo, but it doesn't do more damage, and the ROF peak of the HAR is higher than the minigun ROF. It's primary fire has the same pecularity as the HAR, since you need to wait a bit before having the maximum ROF, this time the secondary fire removes the wait almost entirely without using ammo, since it rotates the barrels.