A good friend of mine who lives in Lapeer and spends a lot of time shooting and cleaning up the Pit found an article about it in his local paper.... Long story short, two things are going on-the locals have been making a shit ton of noise complaints and the State is going to be doing sound testing.
One the noise complaints, it sounds like the neighbors are making them even when there isn't an issue with shooting times but the DNR is tired of dealing with the problem. The sound tests will happen on the 17th where they are going to shut the range down for the day and do god knows what, but according to the article they are looking at this with an eye on either moving the range or shutting it down.
If having this range is I'm portent to you, it might be time to start writing letters and making phone calls. I only get out to the Pit once a year or so since I got my land, but I have fond memories of past trips out there for fun shoots and getting together with friends. It would be a real shame to lose this place.