at present we are facing something that seems to be similar to a WWII fighter with more manoeuvrability. We are using something similar to a single-shot sniper rifle, with a mess of bricks tied to it. What we can d is pick a direction that they are likely to be in, and wait for them to be there. It is terrible. Powered turrets would let us track and lead and such, which sounds wonderful, but is actually woefully insufficient. People don't use single-shot rifles against agile aircraft. Given that we have magic, the mechanics of getting a bullet fired is sort of extreme. It requires very precise repetition, which is the sort of thing that magic is traditionally bad at. A sewing sell would typically be expected to replicate a sewing motion, except perfectly and at impossible speed. A sewing machine will produce a terrible single-sided sewing motion that is prone to unravelling, but can be produced with an extremely repetitive motion and will rip through a line of stiching at a pace the magic sewing spell couldn't hope to compete with. Against the enemy fighters, our cannons just aren't any good. we are fight up-hill to get extreme rate-of-fire. There are lots of tricks that we can pull off, but ultimately none of them will work well enough. But magic can be clever, and we ought to be able to get homing projectiles, effects that directly manifest upon a target, sticky air-webs that spontaneously appear across the sky and catch annoying bugs. Powered turrets would help, but they shouldn't turn the battle around.