Zarya is one of the more complicated characters, as her weapon can be fired in 2 ways. Either using a high damage Beam as her primary fire or particle bombs that can deal damage in an area. But how should you use her primary and secondary fire?
There are 3 ways to use her gun, Primary, Secondary and Hybrid, and I want to go over when to use which.
Zarya’s primary fire deals the highest damage per second and also damages whatever is currently below your crosshair, however its range is limited. You should use her beam if you want something to go down quickly. It’s best for taking down Barriers like Winston’s Shield Projector or Reinhardt’s Shields. Also, it should be used when you need to make sure that you don’t accidentally kill someone else. Sounds odd, but when using Zarya’s ultimate, Graviton Surge it is possible to trap multiple enemies, let’s say a Soldier, McCree, and a Mercy. Now if you would want to deal the maximum amount of damage you would use your secondary fire to hit all 3 of them, but in the worst case, you would kill the McCree and Soldier first, allowing Mercy to resurrect them and completely nullify your ultimate. Or maybe the Soldier drops his biotic field and you won’t be able to damage through that with your secondary fire. In both of those cases, you may want to just laser the Mercy into oblivion. It’s better to get 1 kill out of your Graviton Surge than none at all.
Zarya’s secondary fire doesn’t deal as much damage and takes up a quarter of Zarya’s maximum ammunition, however, it is special in that it knocks targets around and deals damage to multiple targets, while its range can also be a lot higher since it’s a projectile.
You should use Zarya’s secondary fire if you want to build your Graviton Surge from a distance, or if you land a big Graviton Surge and you are confident that you can kill all of them with your secondary fire (Mainly if your energy is high or if your team is helping out, e.g. with an Ana Biotic Grenade). Around 3 enemies in a Graviton surge makes your secondary fire more efficient.
You should not underestimate the knockback effect of her secondary fire, however. It is independent of how much energy you have, and it can throw your opponents aim off.
Dueling a Roadhog? Wait until his reload almost finishes or until his “Take a breather” is almost finished and lob a particle bomb his way. The knockback will throw off his aim and might save you or a teammate a visit towards roadhogs shotgun.
The last way to use her gun is “Hybrid”. With this technique, you abuse the fact that you can lob secondary fire shots even if you have less than 25 ammo. So in theory you could right click with only 1 ammo left, dealing its full damage still. So you can use 76 ammo for 4 particle bombs while using the remaining 24 for your beam. Alternate between primary and secondary fire and with some practice you will get this right. This is what you should do when taking duels, as it ensures you don’t have to reload too much, and you get to benefit from the beams DPS and the bombs knockback throwing their aim off!