Mine came loose maybe slightly worse ive seen other new mws's also with loose receivers out the box my recommendation would be to plop some rubber bands over the pegs on the upper. if you want to close the gap and stop wobble permanently shimstock would be the way to go or possibly tap grub screws on the bottom of the takwdown pegs to push up on the takedown pins but that could most likely weaken the upper when i find a spare for cheap ill give it a go and try