Forum:Spell Deflection

I was wondering how exactly people deflected their opponents curses without using the Shield Charm. It happens many times throughout the novels and movies one for example in Half-Blood Prince Snape deflects Harry's Sectusemprawith only a flick of his wand, is he using Protego as a nonverbal spell? Protego is said to reflect the spell back at the caster and defelcting it would not fall under using Protego. Also in OOTP Lucius Malfoy deflects Bellatrix's Stunning charm so quick it would have been to hard to say or think Protego he was standing beside her and he stopped her from stunning Harry so he wouldn't drop the prophecy.