The whole point of the Darne sling is it is unobtrusive. Because the sling is free to move up and down the length of the barrels, and is not fixed by a hard attachment point on the barrel, like a sling swivel, it works very well in brushy conditions and doesn't snag on anything, or, at least snags on fewer things than my hat does.
It is easily removed, as well, and curls up in a pocket on the vest. I do, however, just leave them in place. There are guys who believe it is blasphemy that a sling can be used on a gun in a grouse woods, but, I do it, regularly, with my little 12.
The 25 year old guy I was didn't really need a sling on his Darne, and my first 20 gauge, didn't have one. But, the 55 year old me sure appreciates having one. My big 12 Darne is going to be restocked next year, and has swivels on it, which, I will retain and use a conventional sling. Even a regular sling is a benefit on a long slog anywhere in western MN or SD.
Gene, contact Geoffroy Gournet if you are still looking. I don't recall if your gun has the fitting installed, or, not, and if it doesn't, It would be an expensive endeavor to have it done. I won't have it done on my 20 gauge R10, but, that is a light gun to begin with.
Best,
Ted
