Im using the stagger perk in the destruction tree. I can't get them to stagger. I could have sworn that ive been able to before. Im using the projectile type spells.

Can't testify for magic, but Giants definitely stagger with bash.

You've never stunned a giant, squatting turtle? Well, don't stare for too long; they're shy. When they stop being shy they get angry and when they're angry, well, I saw one pound a man straight into the ground like a hammer and a nail.

If you're a judo master, and some twelve foot tall man picks a fight with you, your best option is a firearm, large caliber.

If you try to throw your large opponent, physics might dictate a difficult road ahead.

Same with pig-stickers and giants. If you're REALLY good and REALLY lucky, maybe you can stagger him before you become an Easily Identified Flying Object.

I stagger them both with dual cast. They don't stay that way for very long, though.