I have an M&P 15 with some aftermarket 4 rail hand guards. I cant remember what the brand is, they're cheap ones I bought at a gun store from the plastic ziplock bag section. They fit ok and work just fine, but theres quite a bit of vertical play in them. So, when I grab the front grip it seems like the ring that holds the front of the handguards moves up and down. Right now this isnt too annoying, but I'm wondering if this is just because I bought cheap hand guards. It's hard to tell as it looks like this ring is moving, not the handguards alone. Would a higher quality hand guard not move like this, or am I wanting something I can only get from a floating handguard system?