I get a lot questions of people asking about what to do when mounting a TV to a metal stud. PDR Mounts offers a solution for wood stud mounting with our standard lag bolt kit; but for metal studs you cannot safely use lag bolts because they are not designed for this use and will not hold up. What I always recommend is using a "Never Drop Toggle Anchor" from Mcmaster-Carr. What makes these anchors unique is you drill a hole through the drywall and the metal stud large enough for the anchor to slip through sideways, once it is beyond the metal stud you pull on the nylon zip ties and the metal plate flips flat against  the inside of your metal stud. Once the outer nylon ring is flush with your drywall you can trim off the excess nylon strap and you now have a flush nut plate that will never accidentally fall down inside the wall.