I just returned from such a safari. In southern Alberta, just south west of Cardston. Shot 1500 rounds of 22wmr, 1000 x CCI Maxi Mag with Speer TNT bullets (shoot the best in My CZ) 250 each of Remington Premier and Winchester 40grn, jacketed hollow points.
I shot another 100 rounds of 257 Roberts with 85grn Speer TNT HP as well with 42.0grn of WC867 (similar to W748) and CCI 250 LRM primers. This rifle, loves this load and shoots it into 1/2MOA.
I then proceeded to shoot 150 rounds of 6.5x55 out of a Tikka T3. I tried to shoot at a 12 inch gong, my cousin's son had so kindly set up at 400 yards. There was a 15mph cross wind and about 2 feet of mirage. It had been raining heavily, then got blistering hot. I've only seen mirage like that in Africa. I honestly couldn't figure out how to shoot it. Anyway, that didn't stop me from shooting gophers early in the morning and later during calmer conditions. I had about 120 rounds left and proceeded to lay them down on the gopher population. The load was 95grn Hornady V-Max, over 38.5 grns of Varget, my winter coyote load, and proven to be extremely accurate, producing sub 1/2moa groups under all weather and temperature conditions. It isn't a hot load, produces an average 2940fps, but is incredibly consistant and predictable at all ranges, during calm conditions. I could try faster powders but this load is proven to work on coyotes to 400+ meters (witnessed), and on gophers to the same distance. Vertically, they have about the same cross section, when they are sitting up. Any windage errors at long range are immediately apparent by a well placed miss.
I quit counting at 1500 gophers, richardson's ground squirrels. I barely made a dent in the population on 320 acres. They were easy to spot and shoot, because of the wet terrain. It's the first time I've ever seen water flow "out" of a gopher hole.
I also shot a few hundred rounds of 257 Maxi and 22 Hornet, on Martini actions. They both performed very well.
As you can see, you will need a lot of ammunition. I was also informed that depending on elevation and location, the gophers become nocturnal by the end of June to the middle of July. By the middle of August, they are down for the winter. If they aren't, they won't survive the winter. My cousin swears a biologist told him this.
Just to give you an idea of where they are, remember the Grizzly sow that was recently wounded in the hind leg, subsequently put down and her 3 cubs, which were released in Waterton Park? Well he and his wife have pictures of that sow and her young, over a 10+ year period. The big bears, move through that area every spring and though not a common sight, are frequently seen by locals.
It was a great trip. The badgers were having a banner year and the fields showed it. Very few coyotes to be seen though. Strange, nobody was shooting them. Just the odd one, way off in the distance.