If you're talking about my Tikka, it's .223 heavy barrel (varmint model). Don't think they make Varmint's in anything other than .223 and .308.
For the volume of gophers I shoot, .223 just makes sense. I've made one shot hits at 400 yards, so it's plenty accurate for me. 0.40" groups at 100 with very little load development. The WORST load I've tried for this gun was still under an inch at 100. Extremely accurate, and the GRS stock is the best investment I've made. 10 round mags with bullets as long as I want em!