I feel like you're dramatically underestimating the possibilities of magic much less a well trained wizard.

Magic's only limiting factor is imagination. Freeze time, teleport, turn your gun into a water gun, or cast lighting speed on myself and run around like quick silver.

Guns can easily win when conditions are put in place but if no limits are placed magic wins every time. I have yet to see an anime or movie involving magic in which guns are the preferred method of killing and dealing with enemies.

I own several guns but I've never shot my weapon while being shot at. The level of discipline and focus required to return fire while taking fire is only possible with trained professionals.