If you are in NW Indiana, you should be looking at clubs in Michigan, Indiana, and Illinois. There are large clubs at LaFayette, Ind., At Kalamazoo, Michigan, and around Joliet, Illinois. Contact the National Muzzle Loading Rifle Association. Ask for Charter clubs. Then contact the folks. If you are calling on a weekend, folks may just be out of town. You can't know if you have been left a daytime number, or an evening phone number. Try both times. Don't expect people to be home this time of year. Some escape the cold by going South.
Check with local gunsmiths, and gun dealers that carry ML guns and supplies. At the very least, they may know someone else local who is into the sport you can call to get better local information. A local sporting goods store owner used to give folks my name if they were interested in Black Powder guns, gear, or a place to shoot, as he knew I was the attorney for a local club, and an active shooter. I even had police sergeant sending people to me to learn to shoot, because I am an NRA certified trainer.