I agree. A scope with a 20mm objective is very small for most whitetail hunting, but is just fine for turkey hunting because of the time of day that you hunt. Generally speaking, whitetails move during early morning and afternoons, while turkeys move around most of the day or so.
Keep in mind that dangerous game scopes (for hunting animals like elephants, cape buffalo, lion, etc.) usually have 20mm objectives (sometimes maybe a little bit more, but not much).
Mount it and tell us how you like it. I think that you will be pleased. :grin:
Zachary