So I'm still learning about my HK Mark 23 I picked up and have a quick question. I have shot a lot of Glocks and there is a tiny bit of rattle when I shake the gun as the firing pin is loose in the slide by design though i'm curious if it's the same way with the Mark 23, as when I shake it some side to side there seems to be a slight internal rattle like there is something loose in the slide. I'm not talking about the slide to rail fit, that's tight! Is this normal?