What is commonly known as the Northwest Trade Gun was actually known as a "Mackinaw"or "Mackinac" gun due to the LARGE number of them disributed from fort Mackiniac,"back in the day".
Michigan guns had about the same look as Ohio type gun's,and althogh I am by NO means an expert,the original Michigan gun's I've seen all could be typified with Ohio half stock's with a slight Fish Belly to them.
The gun on sitting Fox's site also had 2 cheek pieces on them,what Ray said was a "michigan" feature.