I actually don't use a sling on a hunting shotgun. I find myself carrying it on my shoulder instead of low ready.......When hunting rabbits and pheasant and small game that's bad! Took me one missed shot on a rabbit that tore out of a brush pile for me to take the sling off.
I have no idea who made the one on my 870
It's leather well made and has a wide section.
It's comfortable and works. Although now 20 plus years later it's actually starting to grow a little bit of something on it.
Weight's distributed well so it never feels heavy, hangs in front where I can get to it for a snap shot, and I don't have to hold onto a sling to keep it on me. Much easier ducking under branches without a barrel sticking up over my head. In theory there's a higher risk of plugging the barrel if I took a fall with the barrel pointed down, but in practice it hasn't happened in 5 years of slipping, sliding and falling in the woods, swamps and fields. I carry one of those segmented M16 cleaning rods with me in case it happens.
I keep a no-swivel slip on sling in my bird vest for when I'm tired and have a long slog ahead of me.
Doesn't get much use, but when wanted it's mighty welcome.