Check out Big R on the west end, they have the best selection and prices. Scheels is cheaper on reloading supplies.
The downtown Big R store has a nice gun dept as well, though maybe not quite as much inventory. I have bought most of my guns recently at one or the other of the Big R stores
I bought 1 gun from Scheels and that was a good deal (my every day 357 carry gun) but I will never buy anything from them ever again. I went in there looking for a Saiga 7.62*39 and the salesman told me they could order "anything I wanted." Later, he
finally called me back and told me the store would not sell "assault weapons."
Took this issue all the way to the national gun manager of Scheels and we "agreed" that he wouldn't sell "assault weapons" and I wouldn't buy another thing of any kind from Scheels.
Then I ordered the same gun through a pawn shop gunstore. Later, Big R starting stocking the Saigas (cheaper than what I paid) but of course now the import supply has dried up.
One of the nice things about MT is that you can carry a gun in your car without a permit or anything (and that is pretty common in my observation) and concealed carry is legal without a permit
outside of city limits. Of course, you can get the permit too if you want.
And of course you
have to get a pickup, if you don't already have one.
I read once that there are something like 250K pickups registered in MT among a population of only about 900K, and that doesn't even count all the unregistered pickups being used on ranches.