I have wooden studs, and this (pretty heavy) metal tv mount. The slits it has for attaching to the wall are 5/16" or maybe 6/16" tall.
I bought 1/4" and 5/16" bolts and some washers to go with them, but when I tried to screw them in, I wasn't able to get them to screw in to the holes I had drilled (started at 3/16", then 4/16", then I did 5/16" and the bolts did not seem securely in). I was either unable to ratchet them in or they went in and were feeling loose.
There appears to be about a full inch of drywall (or some material) before the stud, too.
I've seen self-drilling screws, but I feel a screw would not be adequate.
Are bolts the right thing to use here? And if yes, how do I find the right size for the bolts and for the holes?