It sounds like a good way to crack a Glock slide, as some of the harder 1911 slides are prone to do.
Perhaps the Caspian replacement slides are tighter?
Of course there is the old story of the fellow who went to his doctor complaining about an ache when he waved his arm a particular way. The Doctor's advice: Quit waving your arm like that!
Your Glock won't rattle if you don't shake it.
Best wishes,
Daniel