Hi, FG42 slings are cool, and (of course) proprietary to the rifle. They use a WW1 G98 quick-detach sling swivel, a G98 sling parade catch, and a proprietary snap hook. At The Front makes the best repros out there, check their website. Hope this helps.
I bought one and it seems to work just fine on one of my FGs. Metal clip is not pot metal and the leather is not bad. I put some leather conditioner on it to soften it up. I have no complaints.
I do have a repo sling I bought off of GB, it looks pretty good. Trying to get a little closer to a “been there done that” look. I found the link to Bergflak’s Lounge on the forum and sent him a message asking about the fittings on a MG34 sling. He replied back that the buckle for the GEW 98 was what I needed. I think the gew 98 sling loop is also correct for the snap hook that is on the FG42 sling.
Also looking at the FG42 sling ATF makes, but it is currently out of stock. They are waiting on more fittings.
When I get brave I am going to start wearing in the finish on the rifle. Mine is the lacquer finish. Not sure how it will wear in compared to the original paint.