I have a Mauser in 6.5X57 and another in 6.5X.257 Roberts (go figure), and they both are all that is required for deer in my neck of the woods. I have several 16 gauge drillings, but I find it increasingly difficult to locate suitable ammunition for them, whereas 20 gauge is almost as common as 12.
I grew up shooting a 16 gauge and loved its lightness and ease of carrying compared to a 12 gauge of the same model (Browning 5 shot), but years of shooting skeet made me a 20 and 28 gauge fan. My favorite dove gun is a Merkel 12 gauge 201, with 28 gauge tubes.
