.177 all the way. I do have some .22's but are they "needed" for my air gun shooting? Not for me. I culled some bird feeder destroying squirrels today and yesterday using a .177 Walther LGU. No muss, no fuss, quiet, and all that was needed. Modern heavy .177 pellets out of modern high power guns have made the caliber much more versatile than it was in years past, and my family has used the older lower power guns to take many hundreds of squirrels over the years. I no longer hunt but one of the newer guns with heavy pellets would have been deadly as a squirrel rifle in my younger years.