The twin mag SMG is a powerful hitscan SMG with a high fire rate and fast reload, thanks to the twin mag abilities. As of writing this, it is in the reload loot pool with all rarities except for mythic.
There are many strategies to use with this versitaile weapon. Using it's high DPS, you can easily take fresh build peices for extra control over your opponent. A great way to make sure you are using the fast reload during fights is by always fully reloading both mags (Reload twice). This will always ensure that in combat you can keep applying pressure without taking extra time.
Because the Twin Mag SMG dosen't have first shot accuracy, you can stay at a distance since they wont consistently be able to hit you, while you can use an assault rifle or sniper to kill them at range. If you are in close range, try not to 50/50 or get into the same box as them, or they will use the high DPS capabillities to destroy you (true for most spray weapons and not a good idea unless you have a health advantage), so it's best to play defensive.