Well, I (and many others...) wish there was a 'shortcut' when it comes to performing card flourishes. I've seen some guys and their card handling abilities are nothing short of amazing to me.
Simply, 'ya gotta practice...and practice...and practice..."
To perform Lockjaw, you'll need to be proficient with the 'Card Spring' flourish.
Here's a link from 52Kards that I've referred many to. Check it out.
https://www.youtube.com/watch?v=U-GvSSBLVhg
Don't lose confidence. You'll get it soon enough!
Good luck.