The books from the perspective of a HP newbie

[Default_Prophet]

Some of those spells are pretty quick and you’re completely dependent upon the luck of the draw. Be a bit slow and, well, who knows. Sides, it’s easier to cook up an anti-bullet spell than craft a spell-penetrating bullet.

Well. They really haven’t been put up against bullets, It could be that shields stop low velocity stuff but not small mad fast moving objects. Hell most wizards wouldn’t even know what a gun is until they’re dead.