We use our 22.s for shooting gophers in big open, southern Alberta fields. We have shot thousands, maybe 10 thousand or more gophers with the things. Gophers get shot from 5 feet out to 200+ yds with a 22. My longest hits were at around 220 yds.
If you've never seen a gopher up close, they are approximately the size of a 600ml water bottle with a toonie sized head on the top. They rarely sit still for long. They mooch along in the grass and then stand bolt upright for a few seconds before dropping down again. In short grass they offer a horizontal target. In medium grass, a vertical target and in longer grass all you see is the head and only few a few seconds at a time.
With my target rifle I can run headshots at about 70% hit rate out to around 75 yds or so. That requires rapid target acquisition, aim, fire. No screwing around. There is lots of room for error, which means the rifle needs to be very accurate w a good trigger.
As I mentioned earlier, I started out with a borrow Russian TOZ something. Not the same as what yours looks like. It was OK and I was having a great time with it until a friend lent me his Anschutz 64. After a day with that rifle I simply could not go back to the carppy TOZ. The Anschutz trigger, even on the lower end 64 model, is simply a thing of beauty.
Because we are shooting live game, I tested and chose an ammunition that had the best combination of killing power as well as accuracy. In our rifles I settled on Winchester Power Point. Definitely not match ammo, but it eviscerates gophers nicely. I don't remember what size groups our rifles produce with this ammo.
Group size never really mattered on a gopher. It either hit or it didn't. 
This is an Anschutz 64M. They can be had for around $600.
