i have a small collection of these things. at the previous house i had the “wall of guitars” thing going on and i remember having a lot of trouble with the supplied screws / wall plugs. even my lightest guitar was pulling the top screw / plug out of the wall so there’s no way i could trust them for my “real” guitars.
i thought it was probably the house’s fault and got out the big guns in order to get my guitars on the wall. this involved non-matching plugs, screws, and other general ugliness. it was only after we’d moved to this house did i put a little more thought into it; how could it be the house’s / wall’s fault? that makes no sense. and sure enough i was having the same issues here yesterday when trying to install a few hangers in my new studio.
having tried a few other things (and also wanting to be tidier here!) it’s my suspicion that the screw / plug combination is probably fine when you’re attaching something thin to your wall, something with a thickness of say 1/8″. the thing with these particular hangers is that the wood block is 3/4″ thick and so approximately 5/8″ of the screw isn’t actually going into the wall. this means that ultimately the wall plug can’t do its job by expanding behind the drywall and thus holding your precious guitar in place because not enough of the screw is going into the actual wall.
it may be a bit of overkill, but i’ve been able to have consistent success (so far! :-S ) with something much heavier duty, but does the job extremely well, is easy to use and looks just fine. 3/16″ strap toggle anchor is the product.
you drill an enormous 1/4″ hold in your drywall, insert the anchor, pull one of the straps to make the metal anchor perpendicular to the back of the wall, pull the metal anchor tight to the back of the wall, push the nylon lock tight to the front of the wall, and then snap off the nylon straps right up against the wall. you’ll need to make the top hole of your guitar hanger a little bigger so that the (supplied) bolt fits through it. then just screw the wood block to the wall with the bolt. once it’s almost tight, line up the block with your spirit level, mark the bottom hole, and use a regular plug for the original screw.
a lengthy description for a simple topic but hey – hopefully it’s clear enough to understand