The barrel retaining screw or whatever you call it has a 10-32 threaded hole in it for a sling stud. I want a sling stud that SWIVELS, not just the regular studs I've seen. There are 2 reasons for this, if it's a plain stud, it might not line up straight up and down. Even if it does, I'd rather it swiveled so the sling moves easily out of the way when I shoulder it. For my 870, I just bought a magazine cap thingy with the desired function. I can make a sling adapter if I have to, but if they sell one cheap enough, I'd rather buy it.