[@Shadow Daedalus]: Kiritsugu was effective because he was trained in eliminating magi, he had the Origin Bullets, he was unexpected, and he played [i]extremely[/i] dirty. He had a good understanding of magecraft on top of that.

Just using a gun is surprising since a mage isn't going to expect it, but just using a gun isn't good enough to give you an advantage. Volumen Hydragyrum would have blocked [i]any other bullets[/i], and the same goes for your average defensive bounded fields. Reinforcing your body can let you dodge pretty effectively too.

Basically, if you want to make a Magus Hunter who uses guns, they [i]need[/i] to have understanding of Magecraft and training in how to kill magi [i]and[/i] also cheat all the time.