You have to really push that pin down, then it's fairly easy to slide the back plate, REALIZING that you have TWO strings of stuff that can go flying... striker spring column against the back plate and the extractor column which is pushing the pin up to hold the back plate on.
I use a small jeweler's screwdriver because you need something sturdy and small to hold that pin down. You can hold the slide down, muzzle end on the table and use your thumb of that hand to remove and cover the back of the slide to keep things from flying.
After you've done this a few times, it's not scary at all, but if you're not paying attention, things can go flying. I've been lucky so far, 'cause I've done that a few times. 
Wynn
USAF Retired '88, NRA Life Member. Wife USAF Retired '96
Avatar: Wynn re-enlists his wife Desiree, circa 1988 Loring AFB, ME. 42nd BMW, Heavy (SAC) B-52G's
Frédéric Bastiat’s essay, The Law: http://mises.org/books/thelaw.pdf
Thomas Jefferson said
“A government big enough to give you everything you want, is strong enough to take everything you have.”
and
"Peace is that brief glorious moment in history when everybody stands around reloading".