.223 is an excellent varment round, I dont know about those firearms as I am not a big single shot guy. I would suggest a good quality bolt gun but that is not to say a single cant do it just as good, I simply dont know. I would suggest that when you buy a scope to invest a good chunk of change on a very good piece of glass. Often you get what you pay for in optics. Another good calibers to look at is a 22-250.