Unless simply having a magitech weapon renders you bulletproof (which would also mean swordproof) and/or those magitech guns use none of the user's own mana a normal gun is still an effective weapon.

I know that normal guns are usually totally useless in anime, but that's only because the people who use them learned to shoot at the same place Stormtroopers did and the writers need some way to make it so that only the main cast can save the day.

I'm not expecting one shot kills here (metaphoricaly speaking.) It just doesn't make sense to me that extremely effective weapons suddenly become absolutely and hopelessly outclassed in every way once magic enters the picture.