The plating is thin, unlike a cup and core jacketed bullet. The plating is applied through electroplating and is only a few thousandths thick and the core is generally swaged pure, or nearly so, lead. If you drive the bullet much over 1,250 fps, the thin plating will strip through the rifling and tumble. I've driven them a little over 1,300 fps, but that's pretty much the limit for plated handgun bullets. At 1,400+ fps they tumbled wildly.
Plated bullets intended for rifle calibers are plated more heavily, and are usually good to a little over 1,600 fps.
You also don't want to crimp plated pistol bullets too heavily, or you'll cut through the plating, which will strip off the plating and again cause tumbling. I've loaded roughly 60,000 plated bullets in various calibers and I really like them. You just have to treat them as plated and not jacketed.
Hope this helps.
Fred