CA M15A4 Version 4 + Semi loose reciever

[DeltaFrosh]

I was curious whether or not anyone has noticed this and whether there is a remedy to fix it. The upper reciever on the new armlite's from CA seems to be able to move slightly either left or right. Now the front reciever pin simply is locking the upper reciever in place but I have not noticed it having any effect in regards to this minor motion. Now i'm not sure exactly what that thing is called on the side of the reciever (armlite logo side) that lays ontop of both the upper and lower reciever and can be moved either up or down. Does this have anything to do with it? I did move it in the up position where it lays more on the upper reciever but it doesnt have any effect as it seems loose anyway. I'm thinking of possibly adding some kind of buffer between this and the reciever so in a sense it presses against the reciever which would keep it more secure. Any insight into this would be appreciated.