I've shot at Deer Creek on the east side of Missoula. They held the USPSA Area 1 Match a few years ago. Great Match! I started shooting there back in the mid '80's and the range certainly has grown.
I've also shot CAS at the Deep Creek range, which is on the west side of Missoula. Give them a call at 406-543-3075,
Here's a site for a lot of ranges here in MT.
As far as carrying in Missoula, there are others who can probably chime in. I try to stay far away from the place.