I agree with NuclearTech about the Avenger. Both of us mess around with it from time to time on gold. It's not a great weapon, but that doesn't mean it isn't fun to use every once in a while.
When I use it, I put it on a character that has good to great weapon passives and/or powers that complement the weapon itself. Take for example the Quarian Marksman soldier. He has good weapon passives, a quick but effective debuff power (tactical scan), and a power that increases fire rate of the weapon, headshot damage, and accuracy (Marksman). If you stack headshot damage gear (Targeting VI and Vulnerability VI) with the marksman's passives and the headshot modifier from Marksman itself (the headshot modifier on Tactical Scan DOES NOT work because it is bugged), the weapon does decent damage. This is only true if you hit the enemy in the head, more specifically above the "Lethal T" line (Crown of the skull). If you aren't hitting enemies in the head, you won't be dealing a significant amount of damage.
Just as NuclearTech previously stated, it takes good gear and equipment to make it effective on higher level difficulties. I recommend utilizing the Thermal Scope for this setup as it tightens the weapons spread especially when coupled with a Stabilization Mod in your armour gear slot and using Marksman. Does this weapon need stabilization? No, but while in Marksman with double fire rate bonus it does have a little bit of rise at the muzzle. The idea here is get as many pellets to hit the target as possible, and you have a small target to hit with this setup.
On a side note, a good rule of thumb on Gold and Platinum is make sure you always have some method of dealing with armour. Otherwise, you might as well be firing marshmellos at armoured targets. For this I recommend Amour Piercing Rounds versus the piercing mod. On gold, AP II or AP III rounds are more then enough to deal with enemy armour plating. The reason I opt for the AP ammo over the assault rifle piercing mod is so I can use the Assault Rifle Extended Barrel to increase the overall damage output of the weapon. Once again, you have to hit the enemy in the head with this set up even with AP rounds on armoured targets other wise you will only be dealing base weapon + extended barrel + passive damage.
This build works with any projectile weapon that can "headshot" enemy units. Weapons like the Acolyte, Striker, Scorpion, or Venom would be very INEFFECTIVE because they do not have the ability to "headshot". However, this is particularly effective with the weapons like N7 Hurricane, Cerberus Harrier, M-99 Saber, N7 Valkrie, or even the M-11Suppressor.
A lengthy post, yes. But, I hope it helps.






