House,
Holding the gun muzzle down with my left hand, I use a small, stubby flathead screwdriver with my right hand to very gently press in on the tab that secures the backstrap, using the forepiece as leverage. At the same time I exert pressure on the backstrap with my left hand to slide it off.
Of course, it goes without saying, make sure the gun is unloaded.
Hope this helps.