Depends on the size of varmits that you are after. For groundhogs and coyotes at the ranges you mentioned 12x would do the job very well. There are a few 4x12x40 scopes that are not much larger than a 3x9x40, but the ones woth AO are a bit longer. The 4.5x14x40 scopes are very popular now and would also fit your requirements, but with the AO feature they are longer and heavier. Read the specs for field of view at the lower power and pay particular attention to the eye relief number if you are going to use it in the woods as a deer rifle.