Thirty rifles weren't a particularly huge number in the grand scheme of things, especially in a Grand Melee that involved thousands of mechas.
However, when all thirty were being fired at a single target from a relatively safe and unassailable position, thirty rifles were able to almost literally rain down intense rifle beams that could very decisively turn the tide of any battle.
Each volley would take down one or two heavy mechas, and after a mere ten to fifteen seconds, most enemy groups, much less single targets, would be shredded and defeated.
Of course against another powerful group, their strategy probably won't turn out as smooth as that. Sheera Lin, for one, could definitely counter that strategy with a myriad of her own.
I can already imagine the Eternal General sacrificing a few mechas and turning them into shields as her own sharpshooters take down the enemy mechas.
