The horizon stays true to its name and always creates 5 explosions each to the left and right of the impact point, each dealing 10 damage, in a fashion similar to Sinkhole. The most you can do against a single target this way is 40 damage, so firing into groups is better. What this weapon excels at is getting someone down from a hill, since the terrain destruction is pretty good.
Sweeper stretches that horizontal axis to infinity. Once it hits the ground it will fire 2 projectiles perfectly on the horizontal axis of where you hit, one to the left and one to the right. These deal 30 damage each and can only deal friendly fire when the shooter or a teammate is stacked on an opponent that is hit, due to it having an AOE explosion when it hits an enemy tank. They pass through all terrain, meaning a hit anywhere on the map that is on the same height as the enemy will hit. However, it can bounce off bumpers and is affected by black holes. It should be noted that the projectiles on both sides only hit once, meaning maximum damage done is 60, unless the projectiles hit tanks that are stacked on top of each other, hence why Sweeper has an AOE explosion. If you land a perfect shot you do no damage because the shot starts to the left and right of the enemy but doesn't touch it, meaning a miss is required.