The Machine Gun tank and its subclasses are often forgotten by inexperienced players because they're less flashy than some of the tanks you get when going another class. But what the Machine Gun classes lack in flash they make up for in power.
There are only two subclasses that the Machine Gun can build into: the Destroyer and the Gunner. We're going to go into which stats are best suited to each tank as well as general gameplay tips to help you get better with these simple but powerful classes.
Do note these are only my personal opinions after having played Diep.io for a couple months now. You may find you like to use different stat builds or play these classes differently, but these are what I've found to be most effective in the heat of tank battle.
The Destroyer is one of the few classes that has been in Diep.io since the game first started, and it has stayed much the same.
This class has the slowest firing in the game, but the trade off for those slow shots is their high default power and penetration.
Even if you don't max out Bullet Damage and Bullet Penetration, your shots as a Destroyer will still penetrate most other tanks' shots and deal a good amount of damage.
As this class you can shoot through just about any bullet barrage with ease and have a fair amount of HP with just one or two points in Maximum Health so you are durable enough to survive big fights.
These are the standard shooting stats most classes prioritize, but faster-shooting tanks have more leeway. The Destroyer is not one of those.
While you do not necessarily have to max out all of these stats, it is a must that you put maximum points into Bullet Speed and Reload.
The Destroyer is a very slow tank in both movement and shooting, and while their shots are large it's easy for other players to dodge them. Maxing out Bullet Speed and Reload makes it easier for you to actually hit other players.
You can generally feel safe putting 4 or 5 points in Bullet Penetration or Bullet Damage if you want some Health Regen, or Maximum Health instead.
The Destroyer often needs some survivability because its base movespeed is so low, so it may not be a good idea to go full offensive stats. It's a good idea to get some Maximum Health and Health Regen.
One or two points in Movement Speed is often enough, if any at all. This tank's speed will be very low no matter what.
The Gunner is a far cry from the Destroyer. While the Destroyer shoots slowly, the Gunner is very similar to the Triplet class in the Twin tank tree in that it shoots fast and furiously. But that's about where the similarities end.
This class is one I'd consider "sleeper OP"--everyone ignores it because the Twin's classes are so much more flashy, but the Gunner is extremely powerful against almost any other tank.
What makes this class special are its very small bullets. You might think that smaller means worse, but their base damage is quite high, and they have a higher base penetration than any of the Twin tanks. This means the Gunner can focus-fire almost any other class to death in a 1-on-1 fight.
Not only are its tiny death bullets amazing, but it seems to be able to take a beating better than any of the Twin tanks as well. The only downside is, much like the Destroyer, the Gunner moves very slowly.
This baby was made to kill.
The Gunner is most effective with the above stats maxed out, and even more so with Bullet Speed. But if you want to be more durable and move faster by putting stats in health and movement, you don't need to invest many points into Bullet Speed.
It is entirely possible to go full class cannon with the Gunner (ideally with one or two points in Health Regen and Maximum Health and maybe one in Movement Speed) and dominate the scoreboard with ease.
The Gunner is seriously one of the easiest classes to play in Diep.io. Farming and killing other players are both easy tasks.
The Machine Gun and its subclass tanks are stronger than most players give them credit for, especially the Gunner.
For the time being, the Machine Gun is the only class that does not have level 45 options. Hopefully these will be added in time as the most recently added classes, the Stalker and Necromancer, are both very powerful in the hands of good players.
Does the Gunner need an advanced level 45 class to rip and tear your opponents? No, but it would definitely be nice! The Destroyer sorely needs a level 45 class to compete as it is currently one of the weakest tanks in the game, right after Hunter (in my opinion).