Uncharted 2 PS4 Airwalk Glitch Tutorial 

Edit: You can also inverse this! Just keep out the long gun, switch to sidearm and press Journal. The frames are when you see him put the long gun on his back, easier timing.
Just a quick and rushed tutorial but should be good enough. Thanks again to Mattmatt10111 for finding this. You can see ways I have used it to skip big sections of the game here: • Video