I would call the gun club and ask there. I also would run a" found Setter" ad in the local paper, you could look at the "lost" dogs column too. And maybe 1 last call to the shelters-unless you already left your name and numbers with them to get ahold of you. And if still nothing turned up, one has made a sincere good faith effort to find the owner and that is all one can really ask of a person. Oh one last thing-there could be a chance it has a micro chip if implanted under the skin, a vet could check for that.
Then at that point, if you wanted to "adopt" the dog as your own, why not. In the meantime, keep an eye peeled on the gash on leg for infection. And if after a week or 2 of no one coming forth to claim it I would say she is yours.
I've had my dogs lost before, so I was very assertive in calling the pounds, Vets, running an ad, putting up flyers all over. I had 1 dog travel 8 miles in 1 days time from phoned in reports, he ended up 3/4 mile from me after 3 days---his paw pads blistered/worn off, he found some dogs and was so tired he just slept with them dogs, anyways the people a day later happened to see a flyer of mine and called me.
My point is, if a person really cares about the dog-they will make repeated attempts to find it. And if you make a good attempt to find the owner, well... then it's their loss and your gain, and then have a good ol time with your new buddy